• NAME
• SYNOPSIS
• DESCRIPTION
• RETURN VALUES
• CIPHER LISTING
• AEAD INTERFACE
  • GCM and OCB Modes
  • CCM Mode
  • SIV Mode
  • ChaCha20-Poly1305
• NOTES
• BUGS
• EXAMPLES
• SEE ALSO
• HISTORY
• COPYRIGHT

NAME

EVP_CIPHER_fetch, EVP_CIPHER_up_ref, EVP_CIPHER_free, 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_Cipher, EVP_get_cipherbyname, EVP_get_cipherbynid, EVP_get_cipherbyobj, EVP_CIPHER_is_a, EVP_CIPHER_name, EVP_CIPHER_number, EVP_CIPHER_names_do_all, EVP_CIPHER_provider, EVP_CIPHER_nid, EVP_CIPHER_get_params, EVP_CIPHER_gettable_params, 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_name, EVP_CIPHER_CTX_nid, EVP_CIPHER_CTX_get_params, EVP_CIPHER_gettable_ctx_params, EVP_CIPHER_CTX_set_params, EVP_CIPHER_settable_ctx_params, EVP_CIPHER_CTX_block_size, EVP_CIPHER_CTX_key_length, EVP_CIPHER_CTX_iv_length, EVP_CIPHER_CTX_tag_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_CIPHER_do_all_provided - EVP cipher routines

SYNOPSIS

 #include <openssl/evp.h>
 
 EVP_CIPHER *EVP_CIPHER_fetch(OPENSSL_CTX *ctx, const char *algorithm,
                              const char *properties);
 int EVP_CIPHER_up_ref(EVP_CIPHER *cipher);
 void EVP_CIPHER_free(EVP_CIPHER *cipher);
 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, const unsigned char *key, const unsigned char *iv);
 int EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
                       int *outl, const 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, const unsigned char *key, const unsigned char *iv);
 int EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
                       int *outl, const 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, const unsigned char *key, const unsigned char *iv, int enc);
 int EVP_CipherUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
                      int *outl, const 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,
                     const unsigned char *key, const 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,
                     const unsigned char *key, const 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,
                    const unsigned char *key, const unsigned char *iv, int enc);
 int EVP_CipherFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
 
 int EVP_Cipher(EVP_CIPHER_CTX *ctx, unsigned char *out,
                const unsigned char *in, unsigned int inl);
 
 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);
 int EVP_CIPHER_CTX_rand_key(EVP_CIPHER_CTX *ctx, unsigned char *key);
 
 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_number(const EVP_CIPHER *e);
 int EVP_CIPHER_is_a(const EVP_CIPHER *cipher, const char *name);
 void EVP_CIPHER_names_do_all(const EVP_CIPHER *cipher,
                              void (*fn)(const char *name, void *data),
                              void *data);
 const char *EVP_CIPHER_name(const EVP_CIPHER *cipher);
 const OSSL_PROVIDER *EVP_CIPHER_provider(const EVP_CIPHER *cipher);
 int EVP_CIPHER_block_size(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);
 const char *EVP_CIPHER_CTX_name(const EVP_CIPHER_CTX *ctx);
 
 int EVP_CIPHER_get_params(EVP_CIPHER *cipher, OSSL_PARAM params[]);
 int EVP_CIPHER_CTX_set_params(EVP_CIPHER_CTX *ctx, const OSSL_PARAM params[]);
 int EVP_CIPHER_CTX_get_params(EVP_CIPHER_CTX *ctx, OSSL_PARAM params[]);
 const OSSL_PARAM *EVP_CIPHER_gettable_params(const EVP_CIPHER *cipher);
 const OSSL_PARAM *EVP_CIPHER_settable_ctx_params(const EVP_CIPHER *cipher);
 const OSSL_PARAM *EVP_CIPHER_gettable_ctx_params(const EVP_CIPHER *cipher);
 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);
 int EVP_CIPHER_CTX_tag_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);
 
 void EVP_CIPHER_do_all_provided(OPENSSL_CTX *libctx,
                                 void (*fn)(EVP_CIPHER *cipher, void *arg),
                                 void *arg);

DESCRIPTION

The EVP cipher routines are a high level interface to certain symmetric ciphers.

The EVP_CIPHER type is a structure for cipher method implementation.

EVP_CIPHER_fetch() fetches the cipher implementation for the given algorithm from any provider offering it, within the criteria given by the properties. See OSSL_PARAM(3) for the use of OSSL_PARAM as parameter descriptor.

EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key length of a cipher when passed an EVP_CIPHER or EVP_CIPHER_CTX structure. The constant EVP_MAX_KEY_LENGTH is the maximum key length for all ciphers. Note: although EVP_CIPHER_key_length() is fixed for a given cipher, the value of EVP_CIPHER_CTX_key_length() may be different for variable key length ciphers.

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 IV length of a cipher when passed an EVP_CIPHER or EVP_CIPHER_CTX. It will return zero if the cipher does not use an IV. The constant EVP_MAX_IV_LENGTH is the maximum IV length for all ciphers.

EVP_CIPHER_CTX_tag_length() returns the tag length of a AEAD cipher when passed a EVP_CIPHER_CTX. It will return zero if the cipher does not support a tag. It returns a default value if the tag length has not been set.

EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the block size of a cipher when passed an EVP_CIPHER or EVP_CIPHER_CTX structure. The constant EVP_MAX_BLOCK_LENGTH is also the maximum block length for all ciphers.

EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the type of the passed cipher or context. This "type" is the actual NID of the cipher OBJECT IDENTIFIER as such it ignores the cipher parameters and 40 bit RC2 and 128 bit RC2 have the same NID. If the cipher does not have an object identifier or does not have ASN1 support this function will return NID_undef.

EVP_CIPHER_is_a() returns 1 if cipher is an implementation of an algorithm that's identifiable with name, otherwise 0. If cipher is a legacy cipher (it's the return value from the likes of EVP_aes128() rather than the result of an EVP_CIPHER_fetch()), only cipher names registered with the default library context (see RETURN VALUES

EVP_CIPHER_fetch() returns a pointer to a EVP_CIPHER for success and NULL for failure.

Refer to "SEE ALSO" for the full list of ciphers available through the EVP interface.

EVP_enc_null()

Null cipher: does nothing.

AEAD INTERFACE

The EVP interface for Authenticated Encryption with Associated Data (AEAD) modes are subtly altered and several additional ctrl operations are supported depending on the mode specified.

To specify additional authenticated data (AAD), a call to EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made with the output parameter out set to NULL.

When decrypting, the return value of EVP_DecryptFinal() or EVP_CipherFinal() indicates whether the operation was successful. If it does not indicate success, the authentication operation has failed and any output data MUST NOT be used as it is corrupted.

GCM and OCB Modes

The following ctrls are supported in GCM and OCB modes.

EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)

Sets the IV length. This call can only be made before specifying an IV. If not called a default IV length is used.

For GCM AES and OCB AES the default is 12 (i.e. 96 bits). For OCB mode the maximum is 15.

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 OCB, taglen must either be 16 or the value previously set via EVP_CTRL_AEAD_SET_TAG.

EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)

Sets the expected tag to taglen bytes from tag. The tag length can only be set before specifying an IV. taglen must be between 1 and 16 inclusive.

For GCM, this call is only valid when decrypting data.

For OCB, this call is valid when decrypting data to set the expected tag, and before encryption to set the desired tag length.

In OCB mode, calling this before encryption with tag set to NULL sets the tag length. If this is not called prior to encryption, a default tag length is used.

For OCB AES, the default tag length is 16 (i.e. 128 bits). It is also the maximum tag length for OCB.

CCM Mode

The EVP interface for CCM mode is similar to that of the GCM mode but with a few additional requirements and different ctrl values.

For CCM mode, the total plaintext or ciphertext length MUST be passed to EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() with the output and input parameters (in and out) set to NULL and the length passed in the inl parameter.

The following ctrls are supported in CCM mode.

EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)

This call is made to set the expected CCM tag value when decrypting or the length of the tag (with the tag parameter set to NULL) when encrypting. The tag length is often referred to as M. If not set a default value is used (12 for AES). When decrypting, the tag needs to be set before passing in data to be decrypted, but as in GCM and OCB mode, it can be set after passing additional authenticated data (see "AEAD INTERFACE").

EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_CCM_SET_L, ivlen, NULL)

Sets the CCM L value. If not set a default is used (8 for AES).

EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)

Sets the CCM nonce (IV) length. This call can only be made before specifying an nonce value. The nonce length is given by 15 - L so it is 7 by default for AES.

SIV Mode

For SIV mode ciphers the behaviour of the EVP interface is subtly altered and several additional ctrl operations are supported.

To specify any additional authenticated data (AAD) and/or a Nonce, a call to EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made with the output parameter out set to NULL.

RFC5297 states that the Nonce is the last piece of AAD before the actual encrypt/decrypt takes place. The API does not differentiate the Nonce from other AAD.

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 MUST NOT be used as it is corrupted.

The following ctrls are supported in both SIV modes.

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 SIV mode the taglen must be 16.

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 and must be made before any data is processed (e.g. before any EVP_DecryptUpdate() call). For SIV mode the taglen must be 16.

SIV mode makes two passes over the input data, thus, only one call to EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made with out set to a non-NULL value. A call to EVP_Decrypt_Final() or EVP_CipherFinal() is not required, but will indicate if the update operation succeeded.

ChaCha20-Poly1305

The following ctrls are supported for the ChaCha20-Poly1305 AEAD algorithm.

EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)

Sets the nonce length. This call can only be made before specifying the nonce. If not called a default nonce length of 12 (i.e. 96 bits) is used. The maximum nonce length is 12 bytes (i.e. 96-bits). If a nonce of less than 12 bytes is set then the nonce is automatically padded with leading 0 bytes to make it 12 bytes in length.

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).

taglen specified here must be 16 (POLY1305_BLOCK_SIZE, i.e. 128-bits) or less.

EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)

Sets the expected tag to taglen bytes from tag. The tag length can only be set before specifying an IV. taglen must be between 1 and 16 (POLY1305_BLOCK_SIZE) inclusive. This call is only valid when decrypting data.

NOTES

Where possible the EVP interface to symmetric ciphers should be used in preference to the low level interfaces. This is because the code then becomes transparent to the cipher used and much more flexible. Additionally, the EVP interface will ensure the use of platform specific cryptographic acceleration such as AES-NI (the low level interfaces do not provide the guarantee).

PKCS padding works by adding n padding bytes of value n to make the total length of the encrypted data a multiple of the block size. Padding is always added so if the data is already a multiple of the block size n will equal the block size. For example if the block size is 8 and 11 bytes are to be encrypted then 5 padding bytes of value 5 will be added.

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.

There are some differences between functions EVP_CipherInit() and EVP_CipherInit_ex(), significant in some circumstances. EVP_CipherInit() fills the passed context object with zeros. As a consequence, EVP_CipherInit() does not allow step-by-step initialization of the ctx when the key and iv are passed in separate calls. It also means that the flags set for the CTX are removed, and it is especially important for the EVP_CIPHER_CTX_FLAG_WRAP_ALLOW flag treated specially in EVP_CipherInit_ex().

EVP_get_cipherbynid(), and EVP_get_cipherbyobj() are implemented as macros.

BUGS

EVP_MAX_KEY_LENGTH and EVP_MAX_IV_LENGTH only refer to the internal ciphers with default key lengths. If custom ciphers exceed these values the results are unpredictable. This is because it has become standard practice to define a generic key as a fixed unsigned char array containing EVP_MAX_KEY_LENGTH bytes.

The ASN1 code is incomplete (and sometimes inaccurate) it has only been tested for certain common S/MIME ciphers (RC2, DES, triple DES) in CBC mode.

EXAMPLES

Encrypt a string using IDEA:

 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 */
         EVP_CIPHER_CTX_free(ctx);
         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 */
         EVP_CIPHER_CTX_free(ctx);
         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 NUL terminated and may contain embedded
      * NULs.
      */
     out = fopen(outfile, "wb");
     if (out == NULL) {
         /* Error */
         return 0;
     }
     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 \
     -K 000102030405060708090A0B0C0D0E0F -iv 0102030405060708 <filename

General encryption and decryption function example using FILE I/O and AES128 with a 128-bit key:

 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_aes_128_gcm(3), EVP_bf_cbc(3), EVP_cast5_cbc(3), EVP_des_cbc(3), EVP_idea_cbc(3), EVP_rc4(3), EVP_seed_cbc(3), HISTORY

Support for OCB mode was added in OpenSSL 1.1.0.

Licensed under the Apache License 2.0 (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at https://www.openssl.org/source/license.html.