Erlang -- crypto

crypto

Reference Manual

Version 4.6.3

- User's Guide
- Reference Manual
- Release Notes
- PDF
- Top

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### Table of Contents

- crypto (App)
- crypto
  - Top of manual page
  - block_decrypt/3
  - block_decrypt/4
  - block_decrypt/4
  - block_encrypt/3
  - block_encrypt/4
  - block_encrypt/4
  - block_encrypt/4
  - bytes_to_integer/1
  - cipher_info/1
  - cmac/3
  - cmac/4
  - compute_key/4
  - crypto_dyn_iv_init/3
  - crypto_dyn_iv_update/3
  - crypto_init/3
  - crypto_init/4
  - crypto_one_time/4
  - crypto_one_time/5
  - crypto_one_time_aead/6
  - crypto_one_time_aead/7
  - crypto_update/2
  - ec_curve/1
  - ec_curves/0
  - enable_fips_mode/1
  - engine_add/1
  - engine_by_id/1
  - engine_ctrl_cmd_string/3
  - engine_ctrl_cmd_string/4
  - engine_get_all_methods/0
  - engine_get_id/1
  - engine_get_name/1
  - engine_list/0
  - engine_load/3
  - engine_load/4
  - engine_remove/1
  - engine_unload/1
  - ensure_engine_loaded/2
  - ensure_engine_loaded/3
  - ensure_engine_unloaded/1
  - ensure_engine_unloaded/2
  - exor/2
  - generate_key/2
  - generate_key/3
  - hash/2
  - hash_final/1
  - hash_info/1
  - hash_init/1
  - hash_update/2
  - hmac/3
  - hmac/4
  - hmac_final/1
  - hmac_final_n/2
  - hmac_init/2
  - hmac_update/2
  - info_fips/0
  - info_lib/0
  - mac/3
  - mac/4
  - macN/4
  - macN/5
  - mac_final/1
  - mac_finalN/2
  - mac_init/2
  - mac_init/3
  - mac_update/2
  - mod_pow/3
  - next_iv/2
  - next_iv/3
  - poly1305/2
  - private_decrypt/4
  - private_encrypt/4
  - privkey_to_pubkey/2
  - public_decrypt/4
  - public_encrypt/4
  - rand_seed/1
  - rand_seed/0
  - rand_seed_alg/1
  - rand_seed_alg/2
  - rand_seed_alg_s/1
  - rand_seed_alg_s/2
  - rand_seed_s/0
  - rand_uniform/2
  - sign/4
  - sign/5
  - start/0
  - stop/0
  - stream_decrypt/2
  - stream_encrypt/2
  - stream_init/2
  - stream_init/3
  - strong_rand_bytes/1
  - supports/1
  - supports/0
  - verify/5
  - verify/6

# crypto

### Module

crypto

### Module Summary

Crypto Functions

### Description

This module provides a set of cryptographic functions.

Hash functions

  SHA1, SHA2
    Secure Hash Standard [FIPS PUB 180-4]
  SHA3
    SHA-3 Standard: Permutation-Based Hash and Extendable-Output Functions [FIPS PUB 202]
  BLAKE2
    BLAKE2 — fast secure hashing
  MD5
    The MD5 Message Digest Algorithm [RFC 1321]
  MD4
    The MD4 Message Digest Algorithm [RFC 1320]

MACs - Message Authentication Codes

  Hmac functions
    Keyed-Hashing for Message Authentication [RFC 2104]
  Cmac functions
    The AES-CMAC Algorithm [RFC 4493]
  POLY1305
    ChaCha20 and Poly1305 for IETF Protocols [RFC 7539]

Symmetric Ciphers

  DES, 3DES and AES
    Block Cipher Techniques [NIST]
  Blowfish
    Fast Software Encryption, Cambridge Security Workshop Proceedings (December 1993), Springer-Verlag, 1994, pp. 191-204.
  Chacha20
    ChaCha20 and Poly1305 for IETF Protocols [RFC 7539]
  Chacha20_poly1305
    ChaCha20 and Poly1305 for IETF Protocols [RFC 7539]

Modes

  ECB, CBC, CFB, OFB and CTR
    Recommendation for Block Cipher Modes of Operation: Methods and Techniques [NIST SP 800-38A]
  GCM
    Recommendation for Block Cipher Modes of Operation: Galois/Counter Mode (GCM) and GMAC [NIST SP 800-38D]
  CCM
    Recommendation for Block Cipher Modes of Operation: The CCM Mode for Authentication and Confidentiality [NIST SP 800-38C]

Asymetric Ciphers - Public Key Techniques

  RSA
    PKCS #1: RSA Cryptography Specifications [RFC 3447]
  DSS
    Digital Signature Standard (DSS) [FIPS 186-4]
  ECDSA
    Elliptic Curve Digital Signature Algorithm [ECDSA]
  SRP
    The SRP Authentication and Key Exchange System [RFC 2945]

Note

The actual supported algorithms and features depends on their availability in the actual libcrypto used. See the crypto (App) about dependencies.

Enabling FIPS mode will also disable algorithms and features.

The CRYPTO User's Guide has more information on FIPS, Engines and Algorithm Details like key lengths.

### Data Types

#### Ciphers, new API

cipher() = cipher_no_iv() | cipher_iv() | cipher_aead()

cipher_no_iv() =
aes_128_ecb | aes_192_ecb | aes_256_ecb | blowfish_ecb |
des_ecb | rc4

cipher_iv() =
aes_128_cbc | aes_192_cbc | aes_256_cbc | aes_128_cfb128 |
aes_192_cfb128 | aes_256_cfb128 | aes_128_cfb8 |
aes_192_cfb8 | aes_256_cfb8 | aes_128_ctr | aes_192_ctr |
aes_256_ctr | aes_ige256 | blowfish_cbc | blowfish_cfb64 |
blowfish_ofb64 | chacha20 | des_ede3_cbc | des_ede3_cfb |
des_cbc | des_cfb | rc2_cbc

cipher_aead() =
aes_128_ccm | aes_192_ccm | aes_256_ccm | aes_128_gcm |
aes_192_gcm | aes_256_gcm | chacha20_poly1305

Ciphers known by the CRYPTO application when using the new API.

Note that this list might be reduced if the underlying libcrypto does not support all of them.

#### Ciphers, old API

block_cipher_with_iv() =
cbc_cipher() | cfb_cipher() | blowfish_ofb64 | aes_ige256

block_cipher_without_iv() = ecb_cipher()

stream_cipher() = ctr_cipher() | chacha20 | rc4

aead_cipher() = aes_gcm | aes_ccm | chacha20_poly1305

cbc_cipher() =
aes_128_cbc | aes_192_cbc | aes_256_cbc | blowfish_cbc |
des_cbc | des_ede3_cbc | rc2_cbc |
retired_cbc_cipher_aliases()

cfb_cipher() =
aes_128_cfb128 | aes_192_cfb128 | aes_256_cfb128 |
aes_128_cfb8 | aes_192_cfb8 | aes_256_cfb8 | blowfish_cfb64 |
des_cfb | des_ede3_cfb |
retired_cfb_cipher_aliases()

ctr_cipher() =
aes_128_ctr | aes_192_ctr | aes_256_ctr |
retired_ctr_cipher_aliases()

ecb_cipher() =
aes_128_ecb | aes_192_ecb | aes_256_ecb | blowfish_ecb |
retired_ecb_cipher_aliases()

Ciphers known by the CRYPTO application when using the old API.

Note that this list might be reduced if the underlying libcrypto does not support all of them.

retired_cbc_cipher_aliases() =
aes_cbc | aes_cbc128 | aes_cbc256 | des3_cbc | des_ede3

retired_cfb_cipher_aliases() =
aes_cfb8 | aes_cfb128 | des3_cbf | des3_cfb | des_ede3_cbf

retired_ctr_cipher_aliases() = aes_ctr

retired_ecb_cipher_aliases() = aes_ecb

Alternative, old names of ciphers known by the CRYPTO application when using the old API. See Retired cipher names for names to use instead to be prepared for an easy convertion to the new API.

Note that this list might be reduced if the underlying libcrypto does not support all of them.

#### Digests and hash

hash_algorithm() =
sha1() |
sha2() |
sha3() |
blake2() |
ripemd160 |
compatibility_only_hash()

hmac_hash_algorithm() =
sha1() | sha2() | sha3() | compatibility_only_hash()

cmac_cipher_algorithm() =
aes_128_cbc | aes_192_cbc | aes_256_cbc | blowfish_cbc |
des_cbc | des_ede3_cbc | rc2_cbc | aes_128_cfb128 |
aes_192_cfb128 | aes_256_cfb128 | aes_128_cfb8 |
aes_192_cfb8 | aes_256_cfb8

rsa_digest_type() = sha1() | sha2() | md5 | ripemd160

dss_digest_type() = sha1() | sha2()

ecdsa_digest_type() = sha1() | sha2()

sha1() = sha
sha2() = sha224 | sha256 | sha384 | sha512
sha3() = sha3_224 | sha3_256 | sha3_384 | sha3_512
blake2() = blake2b | blake2s

compatibility_only_hash() = md5 | md4

The compatibility_only_hash() algorithms are recommended only for compatibility with existing applications.

#### Elliptic Curves

ec_named_curve() =
brainpoolP160r1 | brainpoolP160t1 | brainpoolP192r1 |
brainpoolP192t1 | brainpoolP224r1 | brainpoolP224t1 |
brainpoolP256r1 | brainpoolP256t1 | brainpoolP320r1 |
brainpoolP320t1 | brainpoolP384r1 | brainpoolP384t1 |
brainpoolP512r1 | brainpoolP512t1 | c2pnb163v1 | c2pnb163v2 |
c2pnb163v3 | c2pnb176v1 | c2pnb208w1 | c2pnb272w1 |
c2pnb304w1 | c2pnb368w1 | c2tnb191v1 | c2tnb191v2 |
c2tnb191v3 | c2tnb239v1 | c2tnb239v2 | c2tnb239v3 |
c2tnb359v1 | c2tnb431r1 | ipsec3 | ipsec4 | prime192v1 |
prime192v2 | prime192v3 | prime239v1 | prime239v2 |
prime239v3 | prime256v1 | secp112r1 | secp112r2 | secp128r1 |
secp128r2 | secp160k1 | secp160r1 | secp160r2 | secp192k1 |
secp192r1 | secp224k1 | secp224r1 | secp256k1 | secp256r1 |
secp384r1 | secp521r1 | sect113r1 | sect113r2 | sect131r1 |
sect131r2 | sect163k1 | sect163r1 | sect163r2 | sect193r1 |
sect193r2 | sect233k1 | sect233r1 | sect239k1 | sect283k1 |
sect283r1 | sect409k1 | sect409r1 | sect571k1 | sect571r1 |
wtls1 | wtls10 | wtls11 | wtls12 | wtls3 | wtls4 | wtls5 |
wtls6 | wtls7 | wtls8 | wtls9
edwards_curve_dh() = x25519 | x448
edwards_curve_ed() = ed25519 | ed448

Note that some curves are disabled if FIPS is enabled.

ec_explicit_curve() =
{Field :: ec_field(),
Curve :: ec_curve(),
BasePoint :: binary(),
Order :: binary(),
CoFactor :: none | binary()}
ec_field() = ec_prime_field() | ec_characteristic_two_field()
ec_curve() =
{A :: binary(), B :: binary(), Seed :: none | binary()}

Parametric curve definition.

ec_prime_field() = {prime_field, Prime :: integer()}
ec_characteristic_two_field() =
{characteristic_two_field,
M :: integer(),
Basis :: ec_basis()}
ec_basis() =
{tpbasis, K :: integer() >= 0} |
{ppbasis,
K1 :: integer() >= 0,
K2 :: integer() >= 0,
K3 :: integer() >= 0} |
onbasis

Curve definition details.

#### Keys

key() = iodata()
des3_key() = [key()]

For keylengths, iv-sizes and blocksizes see the User's Guide.

A key for des3 is a list of three iolists

key_integer() = integer() | binary()

Always binary() when used as return value

#### Public/Private Keys

rsa_public() = [key_integer()]
rsa_private() = [key_integer()]
rsa_params() =
{ModulusSizeInBits :: integer(),
PublicExponent :: key_integer()}

    rsa_public() = [E, N]

    rsa_private() = [E, N, D] | [E, N, D, P1, P2, E1, E2, C]

Where E is the public exponent, N is public modulus and D is the private exponent. The longer key format contains redundant information that will make the calculation faster. P1,P2 are first and second prime factors. E1,E2 are first and second exponents. C is the CRT coefficient. Terminology is taken from RFC 3447.

dss_public() = [key_integer()]
dss_private() = [key_integer()]

    dss_public() = [P, Q, G, Y]

Where P, Q and G are the dss parameters and Y is the public key.

    dss_private() = [P, Q, G, X]

Where P, Q and G are the dss parameters and X is the private key.

ecdsa_public() = key_integer()
ecdsa_private() = key_integer()
ecdsa_params() = ec_named_curve() | ec_explicit_curve()

eddsa_public() = key_integer()
eddsa_private() = key_integer()
eddsa_params() = edwards_curve_ed()

srp_public() = key_integer()
srp_private() = key_integer()

    srp_public() = key_integer()

Where is A or B from SRP design

    srp_private() = key_integer()

Where is a or b from SRP design

srp_gen_params() =
{user, srp_user_gen_params()} | {host, srp_host_gen_params()}
srp_comp_params() =
{user, srp_user_comp_params()} |
{host, srp_host_comp_params()}

    srp_user_gen_params() = [DerivedKey::binary(), Prime::binary(), Generator::binary(), Version::atom()]

    srp_host_gen_params() = [Verifier::binary(), Prime::binary(), Version::atom() ]

    srp_user_comp_params() = [DerivedKey::binary(), Prime::binary(), Generator::binary(), Version::atom() | ScramblerArg::list()]

    srp_host_comp_params() = [Verifier::binary(), Prime::binary(), Version::atom() | ScramblerArg::list()]

Where Verifier is v, Generator is g and Prime is N, DerivedKey is X, and Scrambler is u (optional will be generated if not provided) from SRP design Version = '3' | '6' | '6a'

#### Public Key Ciphers

pk_encrypt_decrypt_algs() = rsa

Algorithms for public key encrypt/decrypt. Only RSA is supported.

pk_encrypt_decrypt_opts() = [rsa_opt()] | rsa_compat_opts()
rsa_opt() =
{rsa_padding, rsa_padding()} |
{signature_md, atom()} |
{rsa_mgf1_md, sha} |
{rsa_oaep_label, binary()} |
{rsa_oaep_md, sha}
rsa_padding() =
rsa_pkcs1_padding | rsa_pkcs1_oaep_padding |
rsa_sslv23_padding | rsa_x931_padding | rsa_no_padding

Options for public key encrypt/decrypt. Only RSA is supported.

Warning

The RSA options are experimental.

The exact set of options and there syntax may be changed without prior notice.

rsa_compat_opts() = [{rsa_pad, rsa_padding()}] | rsa_padding()

Those option forms are kept only for compatibility and should not be used in new code.

#### Public Key Sign and Verify

pk_sign_verify_algs() = rsa | dss | ecdsa | eddsa

Algorithms for sign and verify.

pk_sign_verify_opts() = [rsa_sign_verify_opt()]
rsa_sign_verify_opt() =
{rsa_padding, rsa_sign_verify_padding()} |
{rsa_pss_saltlen, integer()} |
{rsa_mgf1_md, sha2()}
rsa_sign_verify_padding() =
rsa_pkcs1_padding | rsa_pkcs1_pss_padding | rsa_x931_padding |
rsa_no_padding

Options for sign and verify.

Warning

The RSA options are experimental.

The exact set of options and there syntax may be changed without prior notice.

#### Diffie-Hellman Keys and parameters

dh_public() = key_integer()
dh_private() = key_integer()

dh_params() = [key_integer()]

    dh_params() = [P, G] | [P, G, PrivateKeyBitLength]

ecdh_public() = key_integer()
ecdh_private() = key_integer()
ecdh_params() =
ec_named_curve() | edwards_curve_dh() | ec_explicit_curve()

#### Types for Engines

engine_key_ref() =
#{engine := engine_ref(),
key_id := key_id(),
password => password(),
term() => term()}
engine_ref() = term()

The result of a call to engine_load/3.

key_id() = string() | binary()

Identifies the key to be used. The format depends on the loaded engine. It is passed to the ENGINE_load_(private|public)_key functions in libcrypto.

password() = string() | binary()

The password of the key stored in an engine.

engine_method_type() =
engine_method_rsa | engine_method_dsa | engine_method_dh |
engine_method_rand | engine_method_ecdh |
engine_method_ecdsa | engine_method_ciphers |
engine_method_digests | engine_method_store |
engine_method_pkey_meths | engine_method_pkey_asn1_meths |
engine_method_ec
engine_cmnd() = {unicode:chardata(), unicode:chardata()}

Pre and Post commands for engine_load/3 and /4.

#### Internal data types

crypto_state()
hash_state()
hmac_state()
mac_state()
stream_state()

Contexts with an internal state that should not be manipulated but passed between function calls.

#### Error types

run_time_error() = no_return()

The exception error:badarg signifies that one or more arguments are of wrong data type, or are otherwise badly formed.

The exception error:notsup signifies that the algorithm is known but is not supported by current underlying libcrypto or explicitly disabled when building that.

For a list of supported algorithms, see supports/0.

descriptive_error() = no_return()

This is a more developed variant of the older run_time_error().

The exception is:

    	  {Tag, {C_FileName,LineNumber}, Description}

    	   Tag = badarg | notsup | error
    	   C_FileName = string()
    	   LineNumber = integer()
    	   Description = string()

It is like the older type an exception of the error class. In addition they contain a descriptive text in English. That text is targeted to a developer. Examples are "Bad key size" or "Cipher id is not an atom".

The exception tags are:

badarg

  Signifies that one or more arguments are of wrong data type or are otherwise badly formed.

notsup

  Signifies that the algorithm is known but is not supported by current underlying libcrypto or explicitly disabled when building that one.

error

  An error condition that should not occur, for example a memory allocation failed or the underlying cryptolib returned an error code, for example "Can't initialize context, step 1". Thoose text usually needs searching the C-code to be understood.

To catch the exception, use for example:

    	  try crypto:crypto_init(Ciph, Key, IV, true)
    	  catch
    	      error:{Tag, {C_FileName,LineNumber}, Description} ->
    	              do_something(......)
    	      .....
    	  end

### New API

### Exports

crypto_init(Cipher, Key, EncryptFlag) -> State | descriptive_error() | OTP 22.0

### Types

Cipher = cipher_no_iv()
Key = iodata()
EncryptFlag = boolean()
State = crypto_state()

As crypto_init/4 but for ciphers without IVs.

crypto_init(Cipher, Key, IV, EncryptFlag) -> State | descriptive_error() | OTP 22.0

### Types

Cipher = cipher_iv()
Key = IV = iodata()
EncryptFlag = boolean()
State = crypto_state()

Part of the new API. Initializes a series of encryptions or decryptions and creates an internal state with a reference that is returned. The actual encryption or decryption is done by crypto_update/2.

For encryption, set the EncryptFlag to true. For decryption, set it to false.

See examples in the User's Guide.

crypto_update(State, Data) -> Result | descriptive_error() | OTP 22.0

### Types

State = crypto_state()
Data = iodata()
Result = binary()

Part of the new API. It does an actual crypto operation on a part of the full text. If the part is less than a number of full blocks, only the full blocks (possibly none) are encrypted or decrypted and the remaining bytes are saved to the next crypto_update operation. The State should be created with crypto_init/3 or crypto_init/4.

See examples in the User's Guide.

crypto_dyn_iv_init(Cipher, Key, EncryptFlag) -> State | descriptive_error() | OTP 22.0

### Types

Cipher = cipher_iv()
Key = iodata()
EncryptFlag = boolean()
State = crypto_state()

Part of the new API. Initializes a series of encryptions or decryptions where the IV is provided later. The actual encryption or decryption is done by crypto_dyn_iv_update/3.

For encryption, set the EncryptFlag to true. For decryption, set it to false.

crypto_dyn_iv_update(State, Data, IV) -> Result | descriptive_error() | OTP 22.0

### Types

State = crypto_state()
Data = IV = iodata()
Result = binary()

Part of the new API. Do an actual crypto operation on a part of the full text and the IV is supplied for each part. The State should be created with crypto_dyn_iv_init/3.

crypto_one_time(Cipher, Key, Data, EncryptFlag) -> Result | descriptive_error() | OTP 22.0

### Types

Cipher = cipher_no_iv()
Key = Data = iodata()
EncryptFlag = boolean()
Result = binary()

As crypto_one_time/5 but for ciphers without IVs.

crypto_one_time(Cipher, Key, IV, Data, EncryptFlag) -> Result | descriptive_error() | OTP 22.0

### Types

Cipher = cipher_iv()
Key = IV = Data = iodata()
EncryptFlag = boolean()
Result = binary()

Part of the new API. Do a complete encrypt or decrypt of the full text in the argument Data.

For encryption, set the EncryptFlag to true. For decryption, set it to false.

See examples in the User's Guide.

crypto_one_time_aead(Cipher, Key, IV, InText, AAD, EncFlag :: true) -> Result | descriptive_error() | OTP 22.0

crypto_one_time_aead(Cipher, Key, IV, InText, AAD, TagOrTagLength, EncFlag) -> Result | descriptive_error() | OTP 22.0

### Types

Cipher = cipher_aead()
Key = IV = InText = AAD = iodata()
TagOrTagLength = EncryptTagLength | DecryptTag
EncryptTagLength = integer() >= 0
DecryptTag = iodata()
EncFlag = boolean()
Result = EncryptResult | DecryptResult
EncryptResult = {OutCryptoText, OutTag}
DecryptResult = OutPlainText | error
OutCryptoText = OutTag = OutPlainText = binary()

Part of the new API. Do a complete encrypt or decrypt with an AEAD cipher of the full text.

For encryption, set the EncryptFlag to true and set the TagOrTagLength to the wanted size of the tag, that is, the tag length. If the default length is wanted, the crypto_aead/6 form may be used.

For decryption, set the EncryptFlag to false and put the tag to be checked in the argument TagOrTagLength.

See examples in the User's Guide.

supports(Type) -> Support | OTP 22.0

### Types

Type = hashs | ciphers | public_keys | macs | curves | rsa_opts
Support = Hashs | Ciphers | PKs | Macs | Curves | RSAopts
Hashs =
[sha1() |
sha2() |
sha3() |
blake2() |
ripemd160 |
compatibility_only_hash()]
Ciphers = [cipher()]
PKs = [rsa | dss | ecdsa | dh | ecdh | ec_gf2m]
Macs = [hmac | cmac | poly1305]
Curves =
[ec_named_curve() | edwards_curve_dh() | edwards_curve_ed()]
RSAopts = [rsa_sign_verify_opt() | rsa_opt()]

Can be used to determine which crypto algorithms that are supported by the underlying libcrypto library

See hash_info/1 and cipher_info/1 for information about the hash and cipher algorithms.

mac(Type :: poly1305, Key, Data) -> Mac | descriptive_error() | OTP 22.1

### Types

Key = Data = iodata()
Mac = binary()

Short for mac(Type, undefined, Key, Data).

mac(Type, SubType, Key, Data) -> Mac | descriptive_error() | OTP 22.1

### Types

Type = hmac | cmac | poly1305
SubType =
hmac_hash_algorithm() | cmac_cipher_algorithm() | undefined
Key = Data = iodata()
Mac = binary()

Computes a MAC (Message Authentication Code) of type Type from Data.

SubType depends on the MAC Type:

- For hmac it is a hash algorithm, see Algorithm Details in the User's Guide.
- For cmac it is a cipher suitable for cmac, see Algorithm Details in the User's Guide.
- For poly1305 it should be set to undefined or the mac/2 function could be used instead, see Algorithm Details in the User's Guide.

Key is the authentication key with a length according to the Type and SubType. The key length could be found with the hash_info/1 (hmac) for and cipher_info/1 (cmac) functions. For poly1305 the key length is 32 bytes. Note that the cryptographic quality of the key is not checked.

The Mac result will have a default length depending on the Type and SubType. To set a shorter length, use macN/4 or macN/5 instead. The default length is documented in Algorithm Details in the User's Guide.

macN(Type :: poly1305, Key, Data, MacLength) -> Mac | descriptive_error() | OTP 22.1

### Types

Key = Data = iodata()
Mac = binary()
MacLength = integer() >= 1

Short for macN(Type, undefined, Key, Data, MacLength).

macN(Type, SubType, Key, Data, MacLength) -> Mac | descriptive_error() | OTP 22.1

### Types

Type = hmac | cmac | poly1305
SubType =
hmac_hash_algorithm() | cmac_cipher_algorithm() | undefined
Key = Data = iodata()
Mac = binary()
MacLength = integer() >= 1

Computes a MAC (Message Authentication Code) as mac/3 and mac/4 but MacLength will limit the size of the resultant Mac to at most MacLength bytes. Note that if MacLength is greater than the actual number of bytes returned from the underlying hash, the returned hash will have that shorter length instead.

The max MacLength is documented in Algorithm Details in the User's Guide.

mac_init(Type :: poly1305, Key) -> State | descriptive_error() | OTP 22.1

### Types

Key = iodata()
State = mac_state()

Short for mac_init(Type, undefined, Key).

mac_init(Type, SubType, Key) -> State | descriptive_error() | OTP 22.1

### Types

Type = hmac | cmac | poly1305
SubType =
hmac_hash_algorithm() | cmac_cipher_algorithm() | undefined
Key = iodata()
State = mac_state()

Initializes the context for streaming MAC operations.

Type determines which mac algorithm to use in the MAC operation.

SubType depends on the MAC Type:

- For hmac it is a hash algorithm, see Algorithm Details in the User's Guide.
- For cmac it is a cipher suitable for cmac, see Algorithm Details in the User's Guide.
- For poly1305 it should be set to undefined or the mac/2 function could be used instead, see Algorithm Details in the User's Guide.

Key is the authentication key with a length according to the Type and SubType. The key length could be found with the hash_info/1 (hmac) for and cipher_info/1 (cmac) functions. For poly1305 the key length is 32 bytes. Note that the cryptographic quality of the key is not checked.

The returned State should be used in one or more subsequent calls to mac_update/2. The MAC value is finally returned by calling mac_final/1 or mac_finalN/2.

See examples in the User's Guide.

mac_update(State0, Data) -> State | descriptive_error() | OTP 22.1

### Types

Data = iodata()
State0 = State = mac_state()

Updates the MAC represented by State0 using the given Data which could be of any length.

The State0 is the State value originally from a MAC init function, that is mac_init/2, mac_init/3 or a previous call of mac_update/2. The value State0 is returned unchanged by the function as State.

mac_final(State) -> Mac | descriptive_error() | OTP 22.1

### Types

State = mac_state()
Mac = binary()

Finalizes the MAC operation referenced by State. The Mac result will have a default length depending on the Type and SubType in the mac_init/2,3 call. To set a shorter length, use mac_finalN/2 instead. The default length is documented in Algorithm Details in the User's Guide.

mac_finalN(State, MacLength) -> Mac | descriptive_error() | OTP 22.1

### Types

State = mac_state()
MacLength = integer() >= 1
Mac = binary()

Finalizes the MAC operation referenced by State.

Mac will be a binary with at most MacLength bytes. Note that if MacLength is greater than the actual number of bytes returned from the underlying hash, the returned hash will have that shorter length instead.

The max MacLength is documented in Algorithm Details in the User's Guide.

### API kept from previous versions

### Exports

bytes_to_integer(Bin :: binary()) -> integer() | OTP R16B01

Convert binary representation, of an integer, to an Erlang integer.

compute_key(Type, OthersPublicKey, MyPrivateKey, Params) -> SharedSecret | OTP R16B01

### Types

Type = dh | ecdh | srp
SharedSecret = binary()
OthersPublicKey = dh_public() | ecdh_public() | srp_public()
MyPrivateKey =
dh_private() | ecdh_private() | {srp_public(), srp_private()}
Params = dh_params() | ecdh_params() | srp_comp_params()

Computes the shared secret from the private key and the other party's public key. See also public_key:compute_key/2

exor(Bin1 :: iodata(), Bin2 :: iodata()) -> binary() |

Performs bit-wise XOR (exclusive or) on the data supplied.

generate_key(Type, Params) -> {PublicKey, PrivKeyOut} | OTP R16B01

generate_key(Type, Params, PrivKeyIn) -> {PublicKey, PrivKeyOut} | OTP R16B01

### Types

Type = dh | ecdh | rsa | srp
PublicKey =
dh_public() | ecdh_public() | rsa_public() | srp_public()
PrivKeyIn =
undefined |
dh_private() |
ecdh_private() |
rsa_private() |
{srp_public(), srp_private()}
PrivKeyOut =
dh_private() |
ecdh_private() |
rsa_private() |
{srp_public(), srp_private()}
Params =
dh_params() | ecdh_params() | rsa_params() | srp_comp_params()

Generates a public key of type Type. See also public_key:generate_key/1. May raise exception:

- error:badarg: an argument is of wrong type or has an illegal value,
- error:low_entropy: the random generator failed due to lack of secure "randomness",
- error:computation_failed: the computation fails of another reason than low_entropy.

Note

RSA key generation is only available if the runtime was built with dirty scheduler support. Otherwise, attempting to generate an RSA key will raise exception error:notsup.

hash(Type, Data) -> Digest | OTP R15B02

### Types

Type = hash_algorithm()
Data = iodata()
Digest = binary()

Computes a message digest of type Type from Data.

May raise exception error:notsup in case the chosen Type is not supported by the underlying libcrypto implementation.

hash_init(Type) -> State | OTP R15B02

### Types

Type = hash_algorithm()
State = hash_state()

Initializes the context for streaming hash operations. Type determines which digest to use. The returned context should be used as argument to hash_update.

May raise exception error:notsup in case the chosen Type is not supported by the underlying libcrypto implementation.

hash_update(State, Data) -> NewState | OTP R15B02

### Types

State = NewState = hash_state()
Data = iodata()

Updates the digest represented by Context using the given Data. Context must have been generated using hash_init or a previous call to this function. Data can be any length. NewContext must be passed into the next call to hash_update or hash_final.

hash_final(State) -> Digest | OTP R15B02

### Types

State = hash_state()
Digest = binary()

Finalizes the hash operation referenced by Context returned from a previous call to hash_update. The size of Digest is determined by the type of hash function used to generate it.

info_fips() -> not_supported | not_enabled | enabled | OTP 20.0

Provides information about the FIPS operating status of crypto and the underlying libcrypto library. If crypto was built with FIPS support this can be either enabled (when running in FIPS mode) or not_enabled. For other builds this value is always not_supported.

See enable_fips_mode/1 about how to enable FIPS mode.

Warning

In FIPS mode all non-FIPS compliant algorithms are disabled and raise exception error:notsup. Check supports that in FIPS mode returns the restricted list of available algorithms.

enable_fips_mode(Enable) -> Result | OTP 21.1

### Types

Enable = Result = boolean()

Enables (Enable = true) or disables (Enable = false) FIPS mode. Returns true if the operation was successful or false otherwise.

Note that to enable FIPS mode succesfully, OTP must be built with the configure option --enable-fips, and the underlying libcrypto must also support FIPS.

See also info_fips/0.

info_lib() -> [{Name, VerNum, VerStr}] |

### Types

Name = binary()
VerNum = integer()
VerStr = binary()

Provides the name and version of the libraries used by crypto.

Name is the name of the library. VerNum is the numeric version according to the library's own versioning scheme. VerStr contains a text variant of the version.

    > info_lib().
    [{<<"OpenSSL">>,269484095,<<"OpenSSL 1.1.0c  10 Nov 2016"">>}]

Note

From OTP R16 the numeric version represents the version of the OpenSSL header files (openssl/opensslv.h) used when crypto was compiled. The text variant represents the libcrypto library used at runtime. In earlier OTP versions both numeric and text was taken from the library.

hash_info(Type) -> Result | run_time_error() | OTP 22.0

### Types

Type = hash_algorithm()
Result =
#{size := integer(),
block_size := integer(),
type := integer()}

Provides a map with information about block_size, size and possibly other properties of the hash algorithm in question.

For a list of supported hash algorithms, see supports/0.

cipher_info(Type) -> Result | run_time_error() | OTP 22.0

### Types

Type = cipher()
Result =
#{key_length := integer(),
iv_length := integer(),
block_size := integer(),
mode := CipherModes,
type := undefined | integer()}
CipherModes =
undefined | cbc_mode | ccm_mode | cfb_mode | ctr_mode |
ecb_mode | gcm_mode | ige_mode | ocb_mode | ofb_mode |
wrap_mode | xts_mode

Provides a map with information about block_size, key_length, iv_length and possibly other properties of the cipher algorithm in question.

Note

The ciphers aes_cbc, aes_cfb8, aes_cfb128, aes_ctr, aes_ecb, aes_gcm and aes_ccm has no keylength in the Type as opposed to for example aes_128_ctr. They adapt to the length of the key provided in the encrypt and decrypt function. Therefor it is impossible to return a valid keylength in the map.

Always use a Type with an explicit key length,

For a list of supported cipher algorithms, see supports/0.

mod_pow(N, P, M) -> Result | OTP R16B01

### Types

N = P = M = binary() | integer()
Result = binary() | error

Computes the function N^P mod M.

next_iv(Type :: cbc_cipher(), Data) -> NextIVec | OTP R16B01

next_iv(Type :: des_cfb, Data, IVec) -> NextIVec | OTP R16B01

### Types

Data = iodata()
IVec = NextIVec = binary()

Returns the initialization vector to be used in the next iteration of encrypt/decrypt of type Type. Data is the encrypted data from the previous iteration step. The IVec argument is only needed for des_cfb as the vector used in the previous iteration step.

private_decrypt(Algorithm, CipherText, PrivateKey, Options) -> PlainText | OTP R16B01

### Types

Algorithm = pk_encrypt_decrypt_algs()
CipherText = binary()
PrivateKey = rsa_private() | engine_key_ref()
Options = pk_encrypt_decrypt_opts()
PlainText = binary()

Decrypts the CipherText, encrypted with public_encrypt/4 (or equivalent function) using the PrivateKey, and returns the plaintext (message digest). This is a low level signature verification operation used for instance by older versions of the SSL protocol. See also public_key:decrypt_private/[2,3]

private_encrypt(Algorithm, PlainText, PrivateKey, Options) -> CipherText | OTP R16B01

### Types

Algorithm = pk_encrypt_decrypt_algs()
PlainText = binary()
PrivateKey = rsa_private() | engine_key_ref()
Options = pk_encrypt_decrypt_opts()
CipherText = binary()

Encrypts the PlainText using the PrivateKey and returns the ciphertext. This is a low level signature operation used for instance by older versions of the SSL protocol. See also public_key:encrypt_private/[2,3]

public_decrypt(Algorithm, CipherText, PublicKey, Options) -> PlainText | OTP R16B01

### Types

Algorithm = pk_encrypt_decrypt_algs()
CipherText = binary()
PublicKey = rsa_public() | engine_key_ref()
Options = pk_encrypt_decrypt_opts()
PlainText = binary()

Decrypts the CipherText, encrypted with private_encrypt/4(or equivalent function) using the PrivateKey, and returns the plaintext (message digest). This is a low level signature verification operation used for instance by older versions of the SSL protocol. See also public_key:decrypt_public/[2,3]

public_encrypt(Algorithm, PlainText, PublicKey, Options) -> CipherText | OTP R16B01

### Types

Algorithm = pk_encrypt_decrypt_algs()
PlainText = binary()
PublicKey = rsa_public() | engine_key_ref()
Options = pk_encrypt_decrypt_opts()
CipherText = binary()

Encrypts the PlainText (message digest) using the PublicKey and returns the CipherText. This is a low level signature operation used for instance by older versions of the SSL protocol. See also public_key:encrypt_public/[2,3]

rand_seed(Seed :: binary()) -> ok | OTP 17.0

Set the seed for PRNG to the given binary. This calls the RAND_seed function from openssl. Only use this if the system you are running on does not have enough "randomness" built in. Normally this is when strong_rand_bytes/1 raises error:low_entropy

rand_uniform(Lo, Hi) -> N |

### Types

Lo, Hi, N = integer()

Generate a random number N, Lo =< N < Hi. Uses the crypto library pseudo-random number generator. Hi must be larger than Lo.

start() -> ok | {error, Reason :: term()} |

Equivalent to application:start(crypto).

stop() -> ok | {error, Reason :: term()} |

Equivalent to application:stop(crypto).

strong_rand_bytes(N :: integer() >= 0) -> binary() | OTP R14B03

Generates N bytes randomly uniform 0..255, and returns the result in a binary. Uses a cryptographically secure prng seeded and periodically mixed with operating system provided entropy. By default this is the RAND_bytes method from OpenSSL.

May raise exception error:low_entropy in case the random generator failed due to lack of secure "randomness".

rand_seed() -> rand:state() | OTP 20.0

Creates state object for random number generation, in order to generate cryptographically strong random numbers (based on OpenSSL's BN_rand_range), and saves it in the process dictionary before returning it as well. See also rand:seed/1 and rand_seed_s/0.

When using the state object from this function the rand functions using it may raise exception error:low_entropy in case the random generator failed due to lack of secure "randomness".

Example

    _ = crypto:rand_seed(),
    _IntegerValue = rand:uniform(42), % [1; 42]
    _FloatValue = rand:uniform().     % [0.0; 1.0[

rand_seed_s() -> rand:state() | OTP 20.0

Creates state object for random number generation, in order to generate cryptographically strongly random numbers (based on OpenSSL's BN_rand_range). See also rand:seed_s/1.

When using the state object from this function the rand functions using it may raise exception error:low_entropy in case the random generator failed due to lack of secure "randomness".

Note

The state returned from this function cannot be used to get a reproducable random sequence as from the other rand functions, since reproducability does not match cryptographically safe.

The only supported usage is to generate one distinct random sequence from this start state.

rand_seed_alg(Alg) -> rand:state() | OTP 21.0

### Types

Alg = crypto | crypto_cache

Creates state object for random number generation, in order to generate cryptographically strong random numbers, and saves it in the process dictionary before returning it as well. See also rand:seed/1 and rand_seed_alg_s/1.

When using the state object from this function the rand functions using it may raise exception error:low_entropy in case the random generator failed due to lack of secure "randomness".

Example

    _ = crypto:rand_seed_alg(crypto_cache),
    _IntegerValue = rand:uniform(42), % [1; 42]
    _FloatValue = rand:uniform().     % [0.0; 1.0[

rand_seed_alg(Alg, Seed) -> rand:state() | OTP-22.0

### Types

Alg = crypto_aes

Creates a state object for random number generation, in order to generate cryptographically unpredictable random numbers, and saves it in the process dictionary before returning it as well. See also rand_seed_alg_s/2.

Example

    _ = crypto:rand_seed_alg(crypto_aes, "my seed"),
    IntegerValue = rand:uniform(42), % [1; 42]
    FloatValue = rand:uniform(),     % [0.0; 1.0[
    _ = crypto:rand_seed_alg(crypto_aes, "my seed"),
    IntegerValue = rand:uniform(42), % Same values
    FloatValue = rand:uniform().     % again

rand_seed_alg_s(Alg) -> rand:state() | OTP 21.0

### Types

Alg = crypto | crypto_cache

Creates state object for random number generation, in order to generate cryptographically strongly random numbers. See also rand:seed_s/1.

If Alg is crypto this function behaves exactly like rand_seed_s/0.

If Alg is crypto_cache this function fetches random data with OpenSSL's RAND_bytes and caches it for speed using an internal word size of 56 bits that makes calculations fast on 64 bit machines.

When using the state object from this function the rand functions using it may raise exception error:low_entropy in case the random generator failed due to lack of secure "randomness".

The cache size can be changed from its default value using the crypto app's configuration parameter rand_cache_size.

When using the state object from this function the rand functions using it may throw exception low_entropy in case the random generator failed due to lack of secure "randomness".

Note

The state returned from this function cannot be used to get a reproducable random sequence as from the other rand functions, since reproducability does not match cryptographically safe.

In fact since random data is cached some numbers may get reproduced if you try, but this is unpredictable.

The only supported usage is to generate one distinct random sequence from this start state.

rand_seed_alg_s(Alg, Seed) -> rand:state() | OTP 22.0

### Types

Alg = crypto_aes

Creates a state object for random number generation, in order to generate cryptographically unpredictable random numbers. See also rand_seed_alg/1.

To get a long period the Xoroshiro928 generator from the rand module is used as a counter (with period 2^928 - 1) and the generator states are scrambled through AES to create 58-bit pseudo random values.

The result should be statistically completely unpredictable random values, since the scrambling is cryptographically strong and the period is ridiculously long. But the generated numbers are not to be regarded as cryptographically strong since there is no re-keying schedule.

- If you need cryptographically strong random numbers use rand_seed_alg_s/1 with Alg =:= crypto or Alg =:= crypto_cache.

- If you need to be able to repeat the sequence use this function.

- If you do not need the statistical quality of this function, there are faster algorithms in the rand module.

Thanks to the used generator the state object supports the rand:jump/0,1 function with distance 2^512.

Numbers are generated in batches and cached for speed reasons. The cache size can be changed from its default value using the crypto app's configuration parameter rand_cache_size.

ec_curves() -> [EllipticCurve] | OTP 17.0

### Types

EllipticCurve =
ec_named_curve() | edwards_curve_dh() | edwards_curve_ed()

Can be used to determine which named elliptic curves are supported.

ec_curve(CurveName) -> ExplicitCurve | OTP 17.0

### Types

CurveName = ec_named_curve()
ExplicitCurve = ec_explicit_curve()

Return the defining parameters of a elliptic curve.

sign(Algorithm, DigestType, Msg, Key) -> Signature | OTP R16B01

sign(Algorithm, DigestType, Msg, Key, Options) -> Signature | OTP 20.1

### Types

Algorithm = pk_sign_verify_algs()
DigestType =
rsa_digest_type() |
dss_digest_type() |
ecdsa_digest_type() |
none
Msg = iodata() | {digest, iodata()}
Key =
rsa_private() |
dss_private() |
[ecdsa_private() | ecdsa_params()] |
[eddsa_private() | eddsa_params()] |
engine_key_ref()
Options = pk_sign_verify_opts()
Signature = binary()

Creates a digital signature.

The msg is either the binary "cleartext" data to be signed or it is the hashed value of "cleartext" i.e. the digest (plaintext).

Algorithm dss can only be used together with digest type sha.

See also public_key:sign/3.

verify(Algorithm, DigestType, Msg, Signature, Key) -> Result | OTP R16B01

verify(Algorithm, DigestType, Msg, Signature, Key, Options) -> Result | OTP 20.1

### Types

Algorithm = pk_sign_verify_algs()
DigestType =
rsa_digest_type() | dss_digest_type() | ecdsa_digest_type()
Msg = iodata() | {digest, iodata()}
Signature = binary()
Key =
rsa_public() |
dss_public() |
[ecdsa_public() | ecdsa_params()] |
[eddsa_public() | eddsa_params()] |
engine_key_ref()
Options = pk_sign_verify_opts()
Result = boolean()

Verifies a digital signature

The msg is either the binary "cleartext" data to be signed or it is the hashed value of "cleartext" i.e. the digest (plaintext).

Algorithm dss can only be used together with digest type sha.

See also public_key:verify/4.

### Engine API

### Exports

privkey_to_pubkey(Type, EnginePrivateKeyRef) -> PublicKey | OTP 20.2

### Types

Type = rsa | dss
EnginePrivateKeyRef = engine_key_ref()
PublicKey = rsa_public() | dss_public()

Fetches the corresponding public key from a private key stored in an Engine. The key must be of the type indicated by the Type parameter.

engine_get_all_methods() -> Result | OTP 20.2

### Types

Result = [engine_method_type()]

Returns a list of all possible engine methods.

May raise exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

See also the chapter Engine Load in the User's Guide.

engine_load(EngineId, PreCmds, PostCmds) -> Result | OTP 20.2

### Types

EngineId = unicode:chardata()
PreCmds = PostCmds = [engine_cmnd()]
Result =
{ok, Engine :: engine_ref()} | {error, Reason :: term()}

Loads the OpenSSL engine given by EngineId if it is available and then returns ok and an engine handle. This function is the same as calling engine_load/4 with EngineMethods set to a list of all the possible methods. An error tuple is returned if the engine can't be loaded.

The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

See also the chapter Engine Load in the User's Guide.

engine_load(EngineId, PreCmds, PostCmds, EngineMethods) -> Result | OTP 20.2

### Types

EngineId = unicode:chardata()
PreCmds = PostCmds = [engine_cmnd()]
EngineMethods = [engine_method_type()]
Result =
{ok, Engine :: engine_ref()} | {error, Reason :: term()}

Loads the OpenSSL engine given by EngineId if it is available and then returns ok and an engine handle. An error tuple is returned if the engine can't be loaded.

The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

See also the chapter Engine Load in the User's Guide.

engine_unload(Engine) -> Result | OTP 20.2

### Types

Engine = engine_ref()
Result = ok | {error, Reason :: term()}

Unloads the OpenSSL engine given by Engine. An error tuple is returned if the engine can't be unloaded.

The function raises a error:badarg if the parameter is in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

See also the chapter Engine Load in the User's Guide.

engine_by_id(EngineId) -> Result | OTP 21.0.6

### Types

EngineId = unicode:chardata()
Result =
{ok, Engine :: engine_ref()} | {error, Reason :: term()}

Get a reference to an already loaded engine with EngineId. An error tuple is returned if the engine can't be unloaded.

The function raises a error:badarg if the parameter is in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

See also the chapter Engine Load in the User's Guide.

engine_ctrl_cmd_string(Engine, CmdName, CmdArg) -> Result | OTP 20.2

### Types

Engine = term()
CmdName = CmdArg = unicode:chardata()
Result = ok | {error, Reason :: term()}

Sends ctrl commands to the OpenSSL engine given by Engine. This function is the same as calling engine_ctrl_cmd_string/4 with Optional set to false.

The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

engine_ctrl_cmd_string(Engine, CmdName, CmdArg, Optional) -> Result | OTP 20.2

### Types

Engine = term()
CmdName = CmdArg = unicode:chardata()
Optional = boolean()
Result = ok | {error, Reason :: term()}

Sends ctrl commands to the OpenSSL engine given by Engine. Optional is a boolean argument that can relax the semantics of the function. If set to true it will only return failure if the ENGINE supported the given command name but failed while executing it, if the ENGINE doesn't support the command name it will simply return success without doing anything. In this case we assume the user is only supplying commands specific to the given ENGINE so we set this to false.

The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

engine_add(Engine) -> Result | OTP 21.0.6

### Types

Engine = engine_ref()
Result = ok | {error, Reason :: term()}

Add the engine to OpenSSL's internal list.

The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

engine_remove(Engine) -> Result | OTP 21.0.6

### Types

Engine = engine_ref()
Result = ok | {error, Reason :: term()}

Remove the engine from OpenSSL's internal list.

The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

engine_get_id(Engine) -> EngineId | OTP 21.0.6

### Types

Engine = engine_ref()
EngineId = unicode:chardata()

Return the ID for the engine, or an empty binary if there is no id set.

The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

engine_get_name(Engine) -> EngineName | OTP 21.0.6

### Types

Engine = engine_ref()
EngineName = unicode:chardata()

Return the name (eg a description) for the engine, or an empty binary if there is no name set.

The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

engine_list() -> Result | OTP 20.2

### Types

Result = [EngineId :: unicode:chardata()]

List the id's of all engines in OpenSSL's internal list.

It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

See also the chapter Engine Load in the User's Guide.

May raise exception error:notsup in case engine functionality is not supported by the underlying OpenSSL implementation.

ensure_engine_loaded(EngineId, LibPath) -> Result | OTP 21.0.6

### Types

EngineId = LibPath = unicode:chardata()
Result =
{ok, Engine :: engine_ref()} | {error, Reason :: term()}

Loads the OpenSSL engine given by EngineId and the path to the dynamic library implementing the engine. This function is the same as calling ensure_engine_loaded/3 with EngineMethods set to a list of all the possible methods. An error tuple is returned if the engine can't be loaded.

The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

See also the chapter Engine Load in the User's Guide.

ensure_engine_loaded(EngineId, LibPath, EngineMethods) -> Result | OTP 21.0.6

### Types

EngineId = LibPath = unicode:chardata()
EngineMethods = [engine_method_type()]
Result =
{ok, Engine :: engine_ref()} | {error, Reason :: term()}

Loads the OpenSSL engine given by EngineId and the path to the dynamic library implementing the engine. This function differs from the normal engine_load in that sense it also add the engine id to the internal list in OpenSSL. Then in the following calls to the function it just fetch the reference to the engine instead of loading it again. An error tuple is returned if the engine can't be loaded.

The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

See also the chapter Engine Load in the User's Guide.

ensure_engine_unloaded(Engine) -> Result | OTP 21.0.6

### Types

Engine = engine_ref()
Result = ok | {error, Reason :: term()}

Unloads an engine loaded with the ensure_engine_loaded function. It both removes the label from the OpenSSL internal engine list and unloads the engine. This function is the same as calling ensure_engine_unloaded/2 with EngineMethods set to a list of all the possible methods. An error tuple is returned if the engine can't be unloaded.

The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

See also the chapter Engine Load in the User's Guide.

ensure_engine_unloaded(Engine, EngineMethods) -> Result | OTP 21.0.6

### Types

Engine = engine_ref()
EngineMethods = [engine_method_type()]
Result = ok | {error, Reason :: term()}

Unloads an engine loaded with the ensure_engine_loaded function. It both removes the label from the OpenSSL internal engine list and unloads the engine. An error tuple is returned if the engine can't be unloaded.

The function raises a error:badarg if the parameters are in wrong format. It may also raise the exception error:notsup in case there is no engine support in the underlying OpenSSL implementation.

See also the chapter Engine Load in the User's Guide.

### Old API

### Exports

block_encrypt(Type :: block_cipher_without_iv(), Key :: key(), PlainText :: iodata()) -> binary() | run_time_error() | OTP 18.0

Don't

Don't use this function for new programs! Use the-new-api.

Encrypt PlainText according to Type block cipher.

May raise exception error:notsup in case the chosen Type is not supported by the underlying libcrypto implementation.

For keylengths and blocksizes see the User's Guide.

block_decrypt(Type :: block_cipher_without_iv(), Key :: key(), Data :: iodata()) -> binary() | run_time_error() | OTP 18.0

Don't

Don't use this function for new programs! Use the new api.

Decrypt CipherText according to Type block cipher.

May raise exception error:notsup in case the chosen Type is not supported by the underlying libcrypto implementation.

For keylengths and blocksizes see the User's Guide.

block_encrypt(Type, Key, Ivec, PlainText) -> CipherText | Error | OTP R16B01

block_encrypt(AeadType, Key, Ivec, {AAD, PlainText}) -> {CipherText, CipherTag} | Error | OTP R16B01

block_encrypt(aes_gcm | aes_ccm, Key, Ivec, {AAD, PlainText, TagLength}) -> {CipherText, CipherTag} | Error | OTP R16B01

### Types

Type = block_cipher_with_iv()
AeadType = aead_cipher()
Key = key() | des3_key()
PlainText = iodata()
AAD = IVec = CipherText = CipherTag = binary()
TagLength = 1..16
Error = run_time_error()

Don't

Don't use this function for new programs! Use the new api.

Encrypt PlainText according to Type block cipher. IVec is an arbitrary initializing vector.

In AEAD (Authenticated Encryption with Associated Data) mode, encrypt PlainTextaccording to Type block cipher and calculate CipherTag that also authenticates the AAD (Associated Authenticated Data).

May raise exception error:notsup in case the chosen Type is not supported by the underlying libcrypto implementation.

For keylengths, iv-sizes and blocksizes see the User's Guide.

block_decrypt(Type, Key, Ivec, CipherText) -> PlainText | Error | OTP R16B01

block_decrypt(AeadType, Key, Ivec, {AAD, CipherText, CipherTag}) -> PlainText | Error | OTP R16B01

### Types

Type = block_cipher_with_iv()
AeadType = aead_cipher()
Key = key() | des3_key()
PlainText = iodata()
AAD = IVec = CipherText = CipherTag = binary()
Error = BadTag | run_time_error()
BadTag = error

Don't

Don't use this function for new programs! Use the new api.

Decrypt CipherText according to Type block cipher. IVec is an arbitrary initializing vector.

In AEAD (Authenticated Encryption with Associated Data) mode, decrypt CipherTextaccording to Type block cipher and check the authenticity the PlainText and AAD (Associated Authenticated Data) using the CipherTag. May return error if the decryption or validation fail's

May raise exception error:notsup in case the chosen Type is not supported by the underlying libcrypto implementation.

For keylengths, iv-sizes and blocksizes see the User's Guide.

stream_init(Type, Key) -> State | run_time_error() | OTP R16B01

### Types

Type = rc4
Key = iodata()
State = stream_state()

Don't

Don't use this function for new programs! Use the new api.

Initializes the state for use in RC4 stream encryption stream_encrypt and stream_decrypt

For keylengths see the User's Guide.

stream_init(Type, Key, IVec) -> State | run_time_error() | OTP R16B01

### Types

Type = stream_cipher()
Key = iodata()
IVec = binary()
State = stream_state()

Don't

Don't use this function for new programs! Use the new api.

Initializes the state for use in streaming AES encryption using Counter mode (CTR). Key is the AES key and must be either 128, 192, or 256 bits long. IVec is an arbitrary initializing vector of 128 bits (16 bytes). This state is for use with stream_encrypt and stream_decrypt.

For keylengths and iv-sizes see the User's Guide.

stream_encrypt(State, PlainText) -> {NewState, CipherText} | run_time_error() | OTP R16B01

### Types

State = stream_state()
PlainText = iodata()
NewState = stream_state()
CipherText = iodata()

Don't

Don't use this function for new programs! Use the new api.

Encrypts PlainText according to the stream cipher Type specified in stream_init/3. Text can be any number of bytes. The initial State is created using stream_init. NewState must be passed into the next call to stream_encrypt.

stream_decrypt(State, CipherText) -> {NewState, PlainText} | run_time_error() | OTP R16B01

### Types

State = stream_state()
CipherText = iodata()
NewState = stream_state()
PlainText = iodata()

Don't

Don't use this function for new programs! Use the new api.

Decrypts CipherText according to the stream cipher Type specified in stream_init/3. PlainText can be any number of bytes. The initial State is created using stream_init. NewState must be passed into the next call to stream_decrypt.

supports() -> [Support] | OTP R16B01

### Types

Support =
{hashs, Hashs} |
{ciphers, Ciphers} |
{public_keys, PKs} |
{macs, Macs} |
{curves, Curves} |
{rsa_opts, RSAopts}
Hashs =
[sha1() |
sha2() |
sha3() |
blake2() |
ripemd160 |
compatibility_only_hash()]
Ciphers = [cipher()]
PKs = [rsa | dss | ecdsa | dh | ecdh | ec_gf2m]
Macs = [hmac | cmac | poly1305]
Curves =
[ec_named_curve() | edwards_curve_dh() | edwards_curve_ed()]
RSAopts = [rsa_sign_verify_opt() | rsa_opt()]

Don't

Don't use this function for new programs! Use supports/1 in the new api.

Can be used to determine which crypto algorithms that are supported by the underlying libcrypto library

See hash_info/1 and cipher_info/1 for information about the hash and cipher algorithms.

hmac(Type, Key, Data) -> Mac | OTP R16B

hmac(Type, Key, Data, MacLength) -> Mac | OTP R16B

### Types

Type = hmac_hash_algorithm()
Key = Data = iodata()
MacLength = integer()
Mac = binary()

Don't

Don't use this function for new programs! Use mac/4 or macN/5 in the new api.

Computes a HMAC of type Type from Data using Key as the authentication key.

MacLength will limit the size of the resultant Mac.

hmac_init(Type, Key) -> State | OTP R14B03

### Types

Type = hmac_hash_algorithm()
Key = iodata()
State = hmac_state()

Don't

Don't use this function for new programs! Use mac_init/3 in the new api.

Initializes the context for streaming HMAC operations. Type determines which hash function to use in the HMAC operation. Key is the authentication key. The key can be any length.

hmac_update(State, Data) -> NewState | OTP R14B03

### Types

Data = iodata()
State = NewState = hmac_state()

Don't

Don't use this function for new programs! Use mac_update/2 in the new api.

Updates the HMAC represented by Context using the given Data. Context must have been generated using an HMAC init function (such as hmac_init). Data can be any length. NewContext must be passed into the next call to hmac_update or to one of the functions hmac_final and hmac_final_n

Warning

Do not use a Context as argument in more than one call to hmac_update or hmac_final. The semantics of reusing old contexts in any way is undefined and could even crash the VM in earlier releases. The reason for this limitation is a lack of support in the underlying libcrypto API.

hmac_final(State) -> Mac | OTP R14B03

### Types

State = hmac_state()
Mac = binary()

Don't

Don't use this function for new programs! Use mac_final/1 in the new api.

Finalizes the HMAC operation referenced by Context. The size of the resultant MAC is determined by the type of hash function used to generate it.

hmac_final_n(State, HashLen) -> Mac | OTP R14B03

### Types

State = hmac_state()
HashLen = integer()
Mac = binary()

Don't

Don't use this function for new programs! Use mac_finalN/2 in the new api.

Finalizes the HMAC operation referenced by Context. HashLen must be greater than zero. Mac will be a binary with at most HashLen bytes. Note that if HashLen is greater than the actual number of bytes returned from the underlying hash, the returned hash will have fewer than HashLen bytes.

cmac(Type, Key, Data) -> Mac | OTP 20.0

cmac(Type, Key, Data, MacLength) -> Mac | OTP 20.0

### Types

Type =
cbc_cipher() |
cfb_cipher() |
blowfish_cbc | des_ede3 | rc2_cbc
Key = Data = iodata()
MacLength = integer()
Mac = binary()

Don't

Don't use this function for new programs! Use mac/4 or macN/5 in the new api.

Computes a CMAC of type Type from Data using Key as the authentication key.

MacLength will limit the size of the resultant Mac.

poly1305(Key :: iodata(), Data :: iodata()) -> Mac | OTP 21.1

### Types

Mac = binary()

Don't

Don't use this function for new programs! Use mac/3 or macN/4 in the new api.

Computes a POLY1305 message authentication code (Mac) from Data using Key as the authentication key.