EVP_aes_128_cbc_hmac_sha1 (3)
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NAME
EVP_CIPHER_CTX_new, EVP_CIPHER_CTX_reset, EVP_CIPHER_CTX_free, EVP_EncryptInit_ex, EVP_EncryptUpdate, EVP_EncryptFinal_ex, EVP_DecryptInit_ex, EVP_DecryptUpdate, EVP_DecryptFinal_ex, EVP_CipherInit_ex, EVP_CipherUpdate, EVP_CipherFinal_ex, EVP_CIPHER_CTX_set_key_length, EVP_CIPHER_CTX_ctrl, EVP_EncryptInit, EVP_EncryptFinal, EVP_DecryptInit, EVP_DecryptFinal, EVP_CipherInit, EVP_CipherFinal, EVP_get_cipherbyname, EVP_get_cipherbynid, EVP_get_cipherbyobj, EVP_CIPHER_nid, EVP_CIPHER_block_size, EVP_CIPHER_key_length, EVP_CIPHER_iv_length, EVP_CIPHER_flags, EVP_CIPHER_mode, EVP_CIPHER_type, EVP_CIPHER_CTX_cipher, EVP_CIPHER_CTX_nid, EVP_CIPHER_CTX_block_size, EVP_CIPHER_CTX_key_length, EVP_CIPHER_CTX_iv_length, EVP_CIPHER_CTX_get_app_data, EVP_CIPHER_CTX_set_app_data, EVP_CIPHER_CTX_type, EVP_CIPHER_CTX_flags, EVP_CIPHER_CTX_mode, EVP_CIPHER_param_to_asn1, EVP_CIPHER_asn1_to_param, EVP_CIPHER_CTX_set_padding, EVP_enc_null, EVP_des_cbc, EVP_des_ecb, EVP_des_cfb, EVP_des_ofb, EVP_des_ede_cbc, EVP_des_ede, EVP_des_ede_ofb, EVP_des_ede_cfb, EVP_des_ede3_cbc, EVP_des_ede3, EVP_des_ede3_ofb, EVP_des_ede3_cfb, EVP_desx_cbc, EVP_rc4, EVP_rc4_40, EVP_rc4_hmac_md5, EVP_idea_cbc, EVP_idea_ecb, EVP_idea_cfb, EVP_idea_ofb, EVP_rc2_cbc, EVP_rc2_ecb, EVP_rc2_cfb, EVP_rc2_ofb, EVP_rc2_40_cbc, EVP_rc2_64_cbc, EVP_bf_cbc, EVP_bf_ecb, EVP_bf_cfb, EVP_bf_ofb, EVP_cast5_cbc, EVP_cast5_ecb, EVP_cast5_cfb, EVP_cast5_ofb, EVP_rc5_32_12_16_cbc, EVP_rc5_32_12_16_ecb, EVP_rc5_32_12_16_cfb, EVP_rc5_32_12_16_ofb, EVP_aes_128_cbc, EVP_aes_128_ecb, EVP_aes_128_cfb, EVP_aes_128_ofb, EVP_aes_192_cbc, EVP_aes_192_ecb, EVP_aes_192_cfb, EVP_aes_192_ofb, EVP_aes_256_cbc, EVP_aes_256_ecb, EVP_aes_256_cfb, EVP_aes_256_ofb, EVP_aes_128_gcm, EVP_aes_192_gcm, EVP_aes_256_gcm, EVP_aes_128_ccm, EVP_aes_192_ccm, EVP_aes_256_ccm, EVP_aes_128_cbc_hmac_sha1, EVP_aes_256_cbc_hmac_sha1, EVP_aes_128_cbc_hmac_sha256, EVP_aes_256_cbc_hmac_sha256, EVP_chacha20, EVP_chacha20_poly1305 - EVP cipher routinesSYNOPSIS
#include <openssl/evp.h> EVP_CIPHER_CTX *EVP_CIPHER_CTX_new(void); int EVP_CIPHER_CTX_reset(EVP_CIPHER_CTX *ctx); void EVP_CIPHER_CTX_free(EVP_CIPHER_CTX *ctx); int EVP_EncryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type, ENGINE *impl, unsigned char *key, unsigned char *iv); int EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl, unsigned char *in, int inl); int EVP_EncryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl); int EVP_DecryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type, ENGINE *impl, unsigned char *key, unsigned char *iv); int EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl, unsigned char *in, int inl); int EVP_DecryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl); int EVP_CipherInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type, ENGINE *impl, unsigned char *key, unsigned char *iv, int enc); int EVP_CipherUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl, unsigned char *in, int inl); int EVP_CipherFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl); int EVP_EncryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type, unsigned char *key, unsigned char *iv); int EVP_EncryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl); int EVP_DecryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type, unsigned char *key, unsigned char *iv); int EVP_DecryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl); int EVP_CipherInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type, unsigned char *key, unsigned char *iv, int enc); int EVP_CipherFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl); int EVP_CIPHER_CTX_set_padding(EVP_CIPHER_CTX *x, int padding); int EVP_CIPHER_CTX_set_key_length(EVP_CIPHER_CTX *x, int keylen); int EVP_CIPHER_CTX_ctrl(EVP_CIPHER_CTX *ctx, int type, int arg, void *ptr); const EVP_CIPHER *EVP_get_cipherbyname(const char *name); const EVP_CIPHER *EVP_get_cipherbynid(int nid); const EVP_CIPHER *EVP_get_cipherbyobj(const ASN1_OBJECT *a); int EVP_CIPHER_nid(const EVP_CIPHER *e); int EVP_CIPHER_block_size(const EVP_CIPHER *e); int EVP_CIPHER_key_length(const EVP_CIPHER *e) int EVP_CIPHER_key_length(const EVP_CIPHER *e); int EVP_CIPHER_iv_length(const EVP_CIPHER *e); unsigned long EVP_CIPHER_flags(const EVP_CIPHER *e); unsigned long EVP_CIPHER_mode(const EVP_CIPHER *e); int EVP_CIPHER_type(const EVP_CIPHER *ctx); const EVP_CIPHER *EVP_CIPHER_CTX_cipher(const EVP_CIPHER_CTX *ctx); int EVP_CIPHER_CTX_nid(const EVP_CIPHER_CTX *ctx); int EVP_CIPHER_CTX_block_size(const EVP_CIPHER_CTX *ctx); int EVP_CIPHER_CTX_key_length(const EVP_CIPHER_CTX *ctx); int EVP_CIPHER_CTX_iv_length(const EVP_CIPHER_CTX *ctx); void *EVP_CIPHER_CTX_get_app_data(const EVP_CIPHER_CTX *ctx); void EVP_CIPHER_CTX_set_app_data(const EVP_CIPHER_CTX *ctx, void *data); int EVP_CIPHER_CTX_type(const EVP_CIPHER_CTX *ctx); int EVP_CIPHER_CTX_mode(const EVP_CIPHER_CTX *ctx); int EVP_CIPHER_param_to_asn1(EVP_CIPHER_CTX *c, ASN1_TYPE *type); int EVP_CIPHER_asn1_to_param(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
DESCRIPTION
TheEVP_CIPHER_CTX_new() creates a cipher context.
EVP_CIPHER_CTX_free() clears all information from a cipher context and free up any allocated memory associate with it, including ctx itself. This function should be called after all operations using a cipher are complete so sensitive information does not remain in memory.
EVP_EncryptInit_ex() sets up cipher context ctx for encryption with cipher type from
EVP_EncryptUpdate() encrypts inl bytes from the buffer in and writes the encrypted version to out. This function can be called multiple times to encrypt successive blocks of data. The amount of data written depends on the block alignment of the encrypted data: as a result the amount of data written may be anything from zero bytes to (inl + cipher_block_size - 1) so out should contain sufficient room. The actual number of bytes written is placed in outl. It also checks if in and out are partially overlapping, and if they are 0 is returned to indicate failure.
If padding is enabled (the default) then EVP_EncryptFinal_ex() encrypts the ``final'' data, that is any data that remains in a partial block. It uses standard block padding (aka
If padding is disabled then EVP_EncryptFinal_ex() will not encrypt any more data and it will return an error if any data remains in a partial block: that is if the total data length is not a multiple of the block size.
EVP_DecryptInit_ex(), EVP_DecryptUpdate() and EVP_DecryptFinal_ex() are the corresponding decryption operations. EVP_DecryptFinal() will return an error code if padding is enabled and the final block is not correctly formatted. The parameters and restrictions are identical to the encryption operations except that if padding is enabled the decrypted data buffer out passed to EVP_DecryptUpdate() should have sufficient room for (inl + cipher_block_size) bytes unless the cipher block size is 1 in which case inl bytes is sufficient.
EVP_CipherInit_ex(), EVP_CipherUpdate() and EVP_CipherFinal_ex() are functions that can be used for decryption or encryption. The operation performed depends on the value of the enc parameter. It should be set to 1 for encryption, 0 for decryption and -1 to leave the value unchanged (the actual value of 'enc' being supplied in a previous call).
EVP_CIPHER_CTX_reset() clears all information from a cipher context and free up any allocated memory associate with it, except the ctx itself. This function should be called anytime ctx is to be reused for another EVP_CipherInit() / EVP_CipherUpdate() / EVP_CipherFinal() series of calls.
EVP_EncryptInit(), EVP_DecryptInit() and EVP_CipherInit() behave in a similar way to EVP_EncryptInit_ex(), EVP_DecryptInit_ex() and EVP_CipherInit_ex() except the ctx parameter does not need to be initialized and they always use the default cipher implementation.
EVP_EncryptFinal(), EVP_DecryptFinal() and EVP_CipherFinal() are identical to EVP_EncryptFinal_ex(), EVP_DecryptFinal_ex() and EVP_CipherFinal_ex(). In previous releases they also cleaned up the ctx, but this is no longer done and EVP_CIPHER_CTX_clean() must be called to free any context resources.
EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj() return an
EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return the
EVP_CIPHER_CTX_set_padding() enables or disables padding. This function should be called after the context is set up for encryption or decryption with EVP_EncryptInit_ex(), EVP_DecryptInit_ex() or EVP_CipherInit_ex(). By default encryption operations are padded using standard block padding and the padding is checked and removed when decrypting. If the pad parameter is zero then no padding is performed, the total amount of data encrypted or decrypted must then be a multiple of the block size or an error will occur.
EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key length of a cipher when passed an
EVP_CIPHER_CTX_set_key_length() sets the key length of the cipher ctx. If the cipher is a fixed length cipher then attempting to set the key length to any value other than the fixed value is an error.
EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the
EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the block size of a cipher when passed an
EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the type of the passed cipher or context. This ``type'' is the actual
EVP_CIPHER_CTX_cipher() returns the
EVP_CIPHER_mode() and EVP_CIPHER_CTX_mode() return the block cipher mode:
EVP_CIPHER_param_to_asn1() sets the AlgorithmIdentifier ``parameter'' based on the passed cipher. This will typically include any parameters and an
EVP_CIPHER_asn1_to_param() sets the cipher parameters based on an
EVP_CIPHER_CTX_ctrl() allows various cipher specific parameters to be determined and set.
RETURN VALUES
EVP_CIPHER_CTX_new() returns a pointer to a newly createdEVP_EncryptInit_ex(), EVP_EncryptUpdate() and EVP_EncryptFinal_ex() return 1 for success and 0 for failure.
EVP_DecryptInit_ex() and EVP_DecryptUpdate() return 1 for success and 0 for failure. EVP_DecryptFinal_ex() returns 0 if the decrypt failed or 1 for success.
EVP_CipherInit_ex() and EVP_CipherUpdate() return 1 for success and 0 for failure. EVP_CipherFinal_ex() returns 0 for a decryption failure or 1 for success.
EVP_CIPHER_CTX_reset() returns 1 for success and 0 for failure.
EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj() return an
EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return a
EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the block size.
EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key length.
EVP_CIPHER_CTX_set_padding() always returns 1.
EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the
EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the
EVP_CIPHER_CTX_cipher() returns an
EVP_CIPHER_param_to_asn1() and EVP_CIPHER_asn1_to_param() return greater than zero for success and zero or a negative number.
CIPHER LISTING
All algorithms have a fixed key length unless otherwise stated.- EVP_enc_null()
- Null cipher: does nothing.
- EVP_aes_128_cbc(), EVP_aes_128_ecb(), EVP_aes_128_cfb(), EVP_aes_128_ofb()
-
AESwith a 128-bit key inCBC, ECB, CFBandOFBmodes respectively.
- EVP_aes_192_cbc(), EVP_aes_192_ecb(), EVP_aes_192_cfb(), EVP_aes_192_ofb()
-
AESwith a 192-bit key inCBC, ECB, CFBandOFBmodes respectively.
- EVP_aes_256_cbc(), EVP_aes_256_ecb(), EVP_aes_256_cfb(), EVP_aes_256_ofb()
-
AESwith a 256-bit key inCBC, ECB, CFBandOFBmodes respectively.
- EVP_des_cbc(), EVP_des_ecb(), EVP_des_cfb(), EVP_des_ofb()
-
DESinCBC, ECB, CFBandOFBmodes respectively.
- EVP_des_ede_cbc(), EVP_des_ede(), EVP_des_ede_ofb(), EVP_des_ede_cfb()
-
Two key triple DESinCBC, ECB, CFBandOFBmodes respectively.
- EVP_des_ede3_cbc(), EVP_des_ede3(), EVP_des_ede3_ofb(), EVP_des_ede3_cfb()
-
Three key triple DESinCBC, ECB, CFBandOFBmodes respectively.
- EVP_desx_cbc()
-
DESXalgorithm inCBCmode.
- EVP_rc4()
-
RC4stream cipher. This is a variable key length cipher with default key length 128 bits.
- EVP_rc4_40()
-
RC4stream cipher with 40 bit key length. This is obsolete and new code should use EVP_rc4() and the EVP_CIPHER_CTX_set_key_length() function.
- EVP_idea_cbc() EVP_idea_ecb(), EVP_idea_cfb(), EVP_idea_ofb()
-
IDEAencryption algorithm inCBC, ECB, CFBandOFBmodes respectively.
- EVP_rc2_cbc(), EVP_rc2_ecb(), EVP_rc2_cfb(), EVP_rc2_ofb()
-
RC2encryption algorithm inCBC, ECB, CFBandOFBmodes respectively. This is a variable key length cipher with an additional parameter called ``effective key bits'' or ``effective key length''. By default both are set to 128 bits.
- EVP_rc2_40_cbc(), EVP_rc2_64_cbc()
-
RC2algorithm inCBCmode with a default key length and effective key length of 40 and 64 bits. These are obsolete and new code should use EVP_rc2_cbc(), EVP_CIPHER_CTX_set_key_length() and EVP_CIPHER_CTX_ctrl() to set the key length and effective key length.
- EVP_bf_cbc(), EVP_bf_ecb(), EVP_bf_cfb(), EVP_bf_ofb()
-
Blowfish encryption algorithm in CBC, ECB, CFBandOFBmodes respectively. This is a variable key length cipher.
- EVP_cast5_cbc(), EVP_cast5_ecb(), EVP_cast5_cfb(), EVP_cast5_ofb()
-
CASTencryption algorithm inCBC, ECB, CFBandOFBmodes respectively. This is a variable key length cipher.
- EVP_rc5_32_12_16_cbc(), EVP_rc5_32_12_16_ecb(), EVP_rc5_32_12_16_cfb(), EVP_rc5_32_12_16_ofb()
-
RC5encryption algorithm inCBC, ECB, CFBandOFBmodes respectively. This is a variable key length cipher with an additional ``number of rounds'' parameter. By default the key length is set to 128 bits and 12 rounds.
- EVP_aes_128_gcm(), EVP_aes_192_gcm(), EVP_aes_256_gcm()
-
AESGalois Counter Mode (GCM) for 128, 192 and 256 bit keys respectively. These ciphers require additional control operations to function correctly: see the ``GCMandOCBModes'' section below for details.
- EVP_aes_128_ocb(void), EVP_aes_192_ocb(void), EVP_aes_256_ocb(void)
-
Offset Codebook Mode (OCB) for 128, 192 and 256 bit keys respectively. These ciphers require additional control operations to function correctly: see the ``GCMandOCBModes'' section below for details.
- EVP_aes_128_ccm(), EVP_aes_192_ccm(), EVP_aes_256_ccm()
-
AESCounter with CBC-MAC Mode (CCM) for 128, 192 and 256 bit keys respectively. These ciphers require additional control operations to function correctly: seeCCMmode section below for details.
- EVP_chacha20()
-
The ChaCha20 stream cipher. The key length is 256 bits, the IVis 96 bits long.
- EVP_chacha20_poly1305()
-
Authenticated encryption with ChaCha20-Poly1305. Like EVP_chacha20() the key is
256 bits and the IVis 96 bits. This supports additional authenticated data (AAD) and produces a 128 bit authentication tag. See the ``GCMandOCBModes'' section for more information.
GCM and OCB Modes
ForTo specify any additional authenticated data (
When decrypting the return value of EVP_DecryptFinal() or EVP_CipherFinal() indicates if the operation was successful. If it does not indicate success the authentication operation has failed and any output data
The following ctrls are supported in both
EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL);
Sets the
EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag);
Writes taglen bytes of the tag value to the buffer indicated by tag. This call can only be made when encrypting data and after all data has been processed (e.g. after an EVP_EncryptFinal() call). For
EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag);
Sets the expected tag to taglen bytes from tag. This call is only legal when decrypting data. For
In
CCM Mode
The behaviour ofLike
The following ctrls are supported in
EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag);
This call is made to set the expected
EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_CCM_SET_L, ivlen, NULL);
Sets the
EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL);
Sets the
NOTES
Where possible the
When decrypting the final block is checked to see if it has the correct form.
Although the decryption operation can produce an error if padding is enabled, it is not a strong test that the input data or key is correct. A random block has better than 1 in 256 chance of being of the correct format and problems with the input data earlier on will not produce a final decrypt error.
If padding is disabled then the decryption operation will always succeed if the total amount of data decrypted is a multiple of the block size.
The functions EVP_EncryptInit(), EVP_EncryptFinal(), EVP_DecryptInit(), EVP_CipherInit() and EVP_CipherFinal() are obsolete but are retained for compatibility with existing code. New code should use EVP_EncryptInit_ex(), EVP_EncryptFinal_ex(), EVP_DecryptInit_ex(), EVP_DecryptFinal_ex(), EVP_CipherInit_ex() and EVP_CipherFinal_ex() because they can reuse an existing context without allocating and freeing it up on each call.
EVP_get_cipherbynid(), and EVP_get_cipherbyobj() are implemented as macros.
BUGS
For
The
EXAMPLES
Encrypt a string using
int do_crypt(char *outfile) { unsigned char outbuf[1024]; int outlen, tmplen; /* Bogus key and IV: we'd normally set these from * another source. */ unsigned char key[] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15}; unsigned char iv[] = {1,2,3,4,5,6,7,8}; char intext[] = "Some Crypto Text"; EVP_CIPHER_CTX *ctx; FILE *out; ctx = EVP_CIPHER_CTX_new(); EVP_EncryptInit_ex(ctx, EVP_idea_cbc(), NULL, key, iv); if(!EVP_EncryptUpdate(ctx, outbuf, &outlen, intext, strlen(intext))) { /* Error */ return 0; } /* Buffer passed to EVP_EncryptFinal() must be after data just * encrypted to avoid overwriting it. */ if(!EVP_EncryptFinal_ex(ctx, outbuf + outlen, &tmplen)) { /* Error */ return 0; } outlen += tmplen; EVP_CIPHER_CTX_free(ctx); /* Need binary mode for fopen because encrypted data is * binary data. Also cannot use strlen() on it because * it won't be null terminated and may contain embedded * nulls. */ out = fopen(outfile, "wb"); fwrite(outbuf, 1, outlen, out); fclose(out); return 1; }
The ciphertext from the above example can be decrypted using the openssl utility with the command line (shown on two lines for clarity):
openssl idea -d <filename -K 000102030405060708090A0B0C0D0E0F -iv 0102030405060708
General encryption and decryption function example using
int do_crypt(FILE *in, FILE *out, int do_encrypt) { /* Allow enough space in output buffer for additional block */ unsigned char inbuf[1024], outbuf[1024 + EVP_MAX_BLOCK_LENGTH]; int inlen, outlen; EVP_CIPHER_CTX *ctx; /* Bogus key and IV: we'd normally set these from * another source. */ unsigned char key[] = "0123456789abcdeF"; unsigned char iv[] = "1234567887654321"; /* Don't set key or IV right away; we want to check lengths */ ctx = EVP_CIPHER_CTX_new(); EVP_CipherInit_ex(&ctx, EVP_aes_128_cbc(), NULL, NULL, NULL, do_encrypt); OPENSSL_assert(EVP_CIPHER_CTX_key_length(ctx) == 16); OPENSSL_assert(EVP_CIPHER_CTX_iv_length(ctx) == 16); /* Now we can set key and IV */ EVP_CipherInit_ex(ctx, NULL, NULL, key, iv, do_encrypt); for(;;) { inlen = fread(inbuf, 1, 1024, in); if (inlen <= 0) break; if(!EVP_CipherUpdate(ctx, outbuf, &outlen, inbuf, inlen)) { /* Error */ EVP_CIPHER_CTX_free(ctx); return 0; } fwrite(outbuf, 1, outlen, out); } if(!EVP_CipherFinal_ex(ctx, outbuf, &outlen)) { /* Error */ EVP_CIPHER_CTX_free(ctx); return 0; } fwrite(outbuf, 1, outlen, out); EVP_CIPHER_CTX_free(ctx); return 1; }
SEE ALSO
evp(7)HISTORY
Support for
COPYRIGHT
Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.Licensed under the OpenSSL license (the ``License''). You may not use this file except in compliance with the License. You can obtain a copy in the file