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crypto(3erl)

Ericsson AB

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Erlang/OTP manual pages

erlang-crypto

Erlang/OTP cryptographic modules

NAME

crypto - 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.

crypto_opts() = boolean() | [crypto_opt()]

crypto_opt() = {encrypt, boolean()} | {padding, padding()}
Selects encryption ({encrypt,true}) or decryption ({encrypt,false}) in the New API .

padding() = cryptolib_padding() | otp_padding()
This option handles padding in the last block. If not set, no padding is done and any bytes in the last unfilled block is silently discarded.

cryptolib_padding() = none | pkcs_padding
The cryptolib_padding are paddings that may be present in the underlying cryptolib linked to the Erlang/OTP crypto app.
For OpenSSL, see the OpenSSL documentation. and find EVP_CIPHER_CTX_set_padding() in cryptolib for your linked version.

otp_padding() = zero | random
Erlang/OTP adds a either padding of zeroes or padding with random bytes.

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". Those 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


block_encrypt(Type :: block_cipher_without_iv(), Key :: key(), PlainText :: iodata()) -> binary() | run_time_error()
Dont:
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()
Dont:
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
block_encrypt(AeadType, Key, Ivec, {AAD, PlainText}) -> {CipherText, CipherTag} | Error
block_encrypt(aes_gcm | aes_ccm, Key, Ivec, {AAD, PlainText, TagLength}) -> {CipherText, CipherTag} | Error
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()
Dont:
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
block_decrypt(AeadType, Key, Ivec, {AAD, CipherText, CipherTag}) -> PlainText | Error
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
Dont:
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()
Types:
Type = rc4
Key = iodata()
State = stream_state()
Dont:
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()
Types:
Type = stream_cipher()
Key = iodata()
IVec = binary()
State = stream_state()
Dont:
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()
Types:
State = stream_state()
PlainText = iodata()
NewState = stream_state()
CipherText = iodata()
Dont:
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()
Types:
State = stream_state()
CipherText = iodata()
NewState = stream_state()
PlainText = iodata()
Dont:
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]
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()]
Dont:
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

hmac(Type, Key, Data, MacLength) -> Mac
Types:
Type = hmac_hash_algorithm()
Key = Data = iodata()
MacLength = integer()
Mac = binary()
Dont:
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
Types:
Type = hmac_hash_algorithm()
Key = iodata()
State = hmac_state()
Dont:
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
Types:
Data = iodata()
State = NewState = hmac_state()
Dont:
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
Types:
State = hmac_state()
Mac = binary()
Dont:
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
Types:
State = hmac_state()
HashLen = integer()
Mac = binary()
Dont:
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

cmac(Type, Key, Data, MacLength) -> Mac
Types:
Type =
cbc_cipher() |
cfb_cipher() |
blowfish_cbc | des_ede3 | rc2_cbc
Key = Data = iodata()
MacLength = integer()
Mac = binary()
Dont:
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
Types:
Mac = binary()
Dont:
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.

API KEPT FROM PREVIOUS

VERSIONS

ENGINE

API

OLD

API
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