class OpenSSL::Cipher
Provides symmetric algorithms for encryption and decryption. The algorithms that are available depend on the particular version ofOpenSSL that is installed.
Listing all supported algorithms¶↑
A list of supported algorithms can be obtained by
putsOpenSSL::Cipher.ciphers
Instantiating aCipher¶↑
There are several ways to create aCipher instance. Generally, aCipher algorithm is categorized by its name, the key length in bits and the cipher mode to be used. The most generic way to create aCipher is the following
cipher =OpenSSL::Cipher.new('<name>-<key length>-<mode>')
That is, a string consisting of the hyphenated concatenation of the individual components name, key length and mode. Either all uppercase or all lowercase strings may be used, for example:
cipher =OpenSSL::Cipher.new('aes-128-cbc')
Choosing either encryption or decryption mode¶↑
Encryption and decryption are often very similar operations for symmetric algorithms, this is reflected by not having to choose different classes for either operation, both can be done using the same class. Still, after obtaining aCipher instance, we need to tell the instance what it is that we intend to do with it, so we need to call either
cipher.encrypt
or
cipher.decrypt
on theCipher instance. This should be the first call after creating the instance, otherwise configuration that has already been set could get lost in the process.
Choosing a key¶↑
Symmetric encryption requires a key that is the same for the encrypting and for the decrypting party and after initial key establishment should be kept as private information. There are a lot of ways to create insecure keys, the most notable is to simply take a password as the key without processing the password further. A simple and secure way to create a key for a particularCipher is
cipher =OpenSSL::Cipher.new('aes-256-cfb')cipher.encryptkey =cipher.random_key# also sets the generated key on the Cipher
If you absolutely need to use passwords as encryption keys, you should use Password-Based Key Derivation Function 2 (PBKDF2) by generating the key with the help of the functionality provided byOpenSSL::PKCS5.pbkdf2_hmac_sha1 orOpenSSL::PKCS5.pbkdf2_hmac.
Although there isCipher#pkcs5_keyivgen, its use is deprecated and it should only be used in legacy applications because it does not use the newer PKCS#5 v2 algorithms.
Choosing an IV¶↑
The cipher modes CBC, CFB, OFB and CTR all need an “initialization vector”, or short, IV. ECB mode is the only mode that does not require an IV, but there is almost no legitimate use case for this mode because of the fact that it does not sufficiently hide plaintext patterns. Therefore
You should never use ECB mode unless you are absolutely sure that you absolutely need it
Because of this, you will end up with a mode that explicitly requires an IV in any case. Although the IV can be seen as public information, i.e. it may be transmitted in public once generated, it should still stay unpredictable to prevent certain kinds of attacks. Therefore, ideally
Always create a secure random IV for every encryption of your Cipher
A new, random IV should be created for every encryption of data. Think of the IV as a nonce (number used once) - it’s public but random and unpredictable. A secure random IV can be created as follows
cipher =...cipher.encryptkey =cipher.random_keyiv =cipher.random_iv# also sets the generated IV on the Cipher
Although the key is generally a random value, too, it is a bad choice as an IV. There are elaborate ways how an attacker can take advantage of such an IV. As a general rule of thumb, exposing the key directly or indirectly should be avoided at all cost and exceptions only be made with good reason.
CallingCipher#final¶↑
ECB (which should not be used) and CBC are both block-based modes. This means that unlike for the other streaming-based modes, they operate on fixed-size blocks of data, and therefore they require a “finalization” step to produce or correctly decrypt the last block of data by appropriately handling some form of padding. Therefore it is essential to add the output ofOpenSSL::Cipher#final to your encryption/decryption buffer or you will end up with decryption errors or truncated data.
Although this is not really necessary for streaming-mode ciphers, it is still recommended to apply the same pattern of adding the output ofCipher#final there as well - it also enables you to switch between modes more easily in the future.
Encrypting and decrypting some data¶↑
data ="Very, very confidential data"cipher =OpenSSL::Cipher.new('aes-128-cbc')cipher.encryptkey =cipher.random_keyiv =cipher.random_ivencrypted =cipher.update(data)+cipher.final...decipher =OpenSSL::Cipher.new('aes-128-cbc')decipher.decryptdecipher.key =keydecipher.iv =ivplain =decipher.update(encrypted)+decipher.finalputsdata==plain#=> true
Authenticated Encryption and AssociatedData (AEAD)¶↑
If theOpenSSL version used supports it, an Authenticated Encryption mode (such as GCM or CCM) should always be preferred over any unauthenticated mode. Currently,OpenSSL supports AE only in combination with AssociatedData (AEAD) where additional associated data is included in the encryption process to compute a tag at the end of the encryption. This tag will also be used in the decryption process and by verifying its validity, the authenticity of a given ciphertext is established.
This is superior to unauthenticated modes in that it allows to detect if somebody effectively changed the ciphertext after it had been encrypted. This prevents malicious modifications of the ciphertext that could otherwise be exploited to modify ciphertexts in ways beneficial to potential attackers.
Associated data, also called additional authenticated data (AAD), is optionally used where there is additional information, such as headers or some metadata, that must be also authenticated but not necessarily need to be encrypted.
An example using the GCM (Galois/Counter Mode). You have 16 byteskey, 12 bytes (96 bits)nonce and the associated dataauth_data. Be sure not to reuse thekey andnonce pair. Reusing an nonce ruins the security guarantees of GCM mode.
key =OpenSSL::Random.random_bytes(16)nonce =OpenSSL::Random.random_bytes(12)auth_data ="authenticated but unencrypted data"data ="encrypted data"cipher =OpenSSL::Cipher.new('aes-128-gcm').encryptcipher.key =keycipher.iv =noncecipher.auth_data =auth_dataencrypted =cipher.update(data)+cipher.finaltag =cipher.auth_tag(16)
Now you are the receiver. You know thekey and have receivednonce,auth_data,encrypted andtag through an untrusted network. Note that GCM accepts an arbitrary length tag between 1 and 16 bytes. You may additionally need to check that the received tag has the correct length, or you allow attackers to forge a valid single byte tag for the tampered ciphertext with a probability of 1/256.
raise"tag is truncated!"unlesstag.bytesize==16decipher =OpenSSL::Cipher.new('aes-128-gcm').decryptdecipher.key =keydecipher.iv =noncedecipher.auth_tag =tag# could be called at any time before #finaldecipher.auth_data =auth_datadecrypted =decipher.update(encrypted)+decipher.finalputsdata==decrypted#=> true
Note that other AEAD ciphers may require additional steps, such as setting the expected tag length (auth_tag_len=) or the total data length (ccm_data_len=) in advance. Make sure to read the relevant man page for details.
Public Class Methods
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static VALUEossl_s_ciphers(VALUE self){ VALUE ary; ary = rb_ary_new(); OBJ_NAME_do_all_sorted(OBJ_NAME_TYPE_CIPHER_METH, add_cipher_name_to_ary, (void*)ary); return ary;}Returns the names of all available ciphers in an array.
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static VALUEossl_cipher_initialize(VALUE self, VALUE str){ EVP_CIPHER_CTX *ctx; const EVP_CIPHER *cipher; char *name; name = StringValueCStr(str); GetCipherInit(self, ctx); if (ctx) { ossl_raise(rb_eRuntimeError, "Cipher already initialized!"); } AllocCipher(self, ctx); if (!(cipher = EVP_get_cipherbyname(name))) { ossl_raise(rb_eRuntimeError, "unsupported cipher algorithm (%"PRIsVALUE")", str); } if (EVP_CipherInit_ex(ctx, cipher, NULL, NULL, NULL, -1) != 1) ossl_raise(eCipherError, NULL); return self;}The string must contain a valid cipher name like “aes-256-cbc”.
A list of cipher names is available by callingOpenSSL::Cipher.ciphers.
Public Instance Methods
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static VALUEossl_cipher_set_auth_data(VALUE self, VALUE data){ EVP_CIPHER_CTX *ctx; unsigned char *in; long in_len, out_len; StringValue(data); in = (unsigned char *) RSTRING_PTR(data); in_len = RSTRING_LEN(data); GetCipher(self, ctx); if (!(EVP_CIPHER_flags(EVP_CIPHER_CTX_cipher(ctx)) & EVP_CIPH_FLAG_AEAD_CIPHER)) ossl_raise(eCipherError, "AEAD not supported by this cipher"); if (!ossl_cipher_update_long(ctx, NULL, &out_len, in, in_len)) ossl_raise(eCipherError, "couldn't set additional authenticated data"); return data;}Sets additional authenticated data (AAD), also called associated data, for thisCipher. This method is available for AEAD ciphers.
The contents of this field should be non-sensitive data which will be added to the ciphertext to generate the authentication tag which validates the contents of the ciphertext.
This method must be called afterkey= andiv= have been set, but before starting actual encryption or decryption withupdate. In some cipher modes,auth_tag_len= andccm_data_len= may also need to be called before this method.
See also the “AEAD Interface” section of the man page EVP_EncryptInit(3). This method internally calls EVP_CipherUpdate() with the output buffer set to NULL.
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static VALUEossl_cipher_get_auth_tag(int argc, VALUE *argv, VALUE self){ VALUE vtag_len, ret; EVP_CIPHER_CTX *ctx; int tag_len = 16; rb_scan_args(argc, argv, "01", &vtag_len); if (NIL_P(vtag_len)) vtag_len = rb_attr_get(self, id_auth_tag_len); if (!NIL_P(vtag_len)) tag_len = NUM2INT(vtag_len); GetCipher(self, ctx); if (!(EVP_CIPHER_flags(EVP_CIPHER_CTX_cipher(ctx)) & EVP_CIPH_FLAG_AEAD_CIPHER)) ossl_raise(eCipherError, "authentication tag not supported by this cipher"); ret = rb_str_new(NULL, tag_len); if (!EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, tag_len, RSTRING_PTR(ret))) ossl_raise(eCipherError, "retrieving the authentication tag failed"); return ret;}Gets the generated authentication tag. This method is available for AEAD ciphers, and should be called after encryption has been finalized by callingfinal.
The returned tag will betag_len bytes long. Some cipher modes require the desired length in advance using a separate call toauth_tag_len=, before starting encryption.
See also the “AEAD Interface” section of the man page EVP_EncryptInit(3). This method internally calls EVP_CIPHER_CTX_ctrl() with EVP_CTRL_AEAD_GET_TAG.
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static VALUEossl_cipher_set_auth_tag(VALUE self, VALUE vtag){ EVP_CIPHER_CTX *ctx; unsigned char *tag; int tag_len; StringValue(vtag); tag = (unsigned char *) RSTRING_PTR(vtag); tag_len = RSTRING_LENINT(vtag); GetCipher(self, ctx); if (!(EVP_CIPHER_flags(EVP_CIPHER_CTX_cipher(ctx)) & EVP_CIPH_FLAG_AEAD_CIPHER)) ossl_raise(eCipherError, "authentication tag not supported by this cipher"); if (!EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, tag_len, tag)) ossl_raise(eCipherError, "unable to set AEAD tag"); return vtag;}Sets the authentication tag to verify the integrity of the ciphertext.
The authentication tag must be set beforefinal is called. The tag is verified during thefinal call.
Note that, for CCM mode and OCB mode, the expected length of the tag must be set before starting decryption by a separate call toauth_tag_len=. The content of the tag can be provided at any time beforefinal is called.
NOTE: The caller must ensure that theString passed to this method has the desired length. Some cipher modes support variable tag lengths, and this method may accept a truncated tag without raising an exception.
See also the “AEAD Interface” section of the man page EVP_EncryptInit(3). This method internally calls EVP_CIPHER_CTX_ctrl() with EVP_CTRL_AEAD_SET_TAG.
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static VALUEossl_cipher_set_auth_tag_len(VALUE self, VALUE vlen){ int tag_len = NUM2INT(vlen); EVP_CIPHER_CTX *ctx; GetCipher(self, ctx); if (!(EVP_CIPHER_flags(EVP_CIPHER_CTX_cipher(ctx)) & EVP_CIPH_FLAG_AEAD_CIPHER)) ossl_raise(eCipherError, "AEAD not supported by this cipher"); if (!EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, tag_len, NULL)) ossl_raise(eCipherError, "unable to set authentication tag length"); /* for #auth_tag */ rb_ivar_set(self, id_auth_tag_len, INT2NUM(tag_len)); return vlen;}Sets the length of the expected authentication tag for thisCipher. This method is available for some of AEAD ciphers that require the length to be set before starting encryption or decryption, such as CCM mode or OCB mode.
For CCM mode and OCB mode, the tag length must be set beforeiv= is set.
See also the “AEAD Interface” section of the man page EVP_EncryptInit(3). This method internally calls EVP_CIPHER_CTX_ctrl() with EVP_CTRL_AEAD_SET_TAG and a NULL buffer.
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static VALUEossl_cipher_is_authenticated(VALUE self){ EVP_CIPHER_CTX *ctx; GetCipher(self, ctx); return (EVP_CIPHER_flags(EVP_CIPHER_CTX_cipher(ctx)) & EVP_CIPH_FLAG_AEAD_CIPHER) ? Qtrue : Qfalse;}Indicates whether thisCipher instance uses an AEAD mode.
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static VALUEossl_cipher_block_size(VALUE self){ EVP_CIPHER_CTX *ctx; GetCipher(self, ctx); return INT2NUM(EVP_CIPHER_CTX_block_size(ctx));}Returns the size in bytes of the blocks on which thisCipher operates on.
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static VALUEossl_cipher_set_ccm_data_len(VALUE self, VALUE data_len){ int in_len, out_len; EVP_CIPHER_CTX *ctx; in_len = NUM2INT(data_len); GetCipher(self, ctx); if (EVP_CipherUpdate(ctx, NULL, &out_len, NULL, in_len) != 1) ossl_raise(eCipherError, NULL); return data_len;}Sets the total length of the plaintext / ciphertext message that will be processed byupdate in CCM mode.
Make sure to call this method afterkey= andiv= have been set, and beforeauth_data= orupdate are called.
This method is only available for CCM mode ciphers.
See also the “AEAD Interface” section of the man page EVP_EncryptInit(3).
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static VALUEossl_cipher_final(VALUE self){ EVP_CIPHER_CTX *ctx; int out_len; VALUE str; GetCipher(self, ctx); str = rb_str_new(0, EVP_CIPHER_CTX_block_size(ctx)); if (!EVP_CipherFinal_ex(ctx, (unsigned char *)RSTRING_PTR(str), &out_len)) { /* For AEAD ciphers, this is likely an authentication failure */ if (EVP_CIPHER_flags(EVP_CIPHER_CTX_cipher(ctx)) & EVP_CIPH_FLAG_AEAD_CIPHER) { /* For AEAD ciphers, EVP_CipherFinal_ex failures are authentication tag verification failures */ ossl_raise(eAuthTagError, "AEAD authentication tag verification failed"); } else { /* For non-AEAD ciphers */ ossl_raise(eCipherError, "cipher final failed"); } } assert(out_len <= RSTRING_LEN(str)); rb_str_set_len(str, out_len); return str;}Returns the remaining data held in the cipher object. Further calls toCipher#update orCipher#final are invalid. This call should always be made as the last call of an encryption or decryption operation, after having fed the entire plaintext or ciphertext to theCipher instance.
When encrypting using an AEAD cipher, the authentication tag can be retrieved byauth_tag afterfinal has been called.
When decrypting using an AEAD cipher, this method will verify the integrity of the ciphertext and the associated data with the authentication tag, which must be set byauth_tag= prior to calling this method. If the verification fails,CipherError will be raised.
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static VALUEossl_cipher_set_iv(VALUE self, VALUE iv){ EVP_CIPHER_CTX *ctx; int iv_len = 0; StringValue(iv); GetCipher(self, ctx); if (EVP_CIPHER_flags(EVP_CIPHER_CTX_cipher(ctx)) & EVP_CIPH_FLAG_AEAD_CIPHER) iv_len = (int)(VALUE)EVP_CIPHER_CTX_get_app_data(ctx); if (!iv_len) iv_len = EVP_CIPHER_CTX_iv_length(ctx); if (RSTRING_LEN(iv) != iv_len) ossl_raise(rb_eArgError, "iv must be %d bytes", iv_len); if (EVP_CipherInit_ex(ctx, NULL, NULL, NULL, (unsigned char *)RSTRING_PTR(iv), -1) != 1) ossl_raise(eCipherError, NULL); return iv;}Sets the cipher IV. Please note that since you should never be using ECB mode, an IV is always explicitly required and should be set prior to encryption. The IV itself can be safely transmitted in public.
This method expects theString to have the length equal toiv_len. To use a different IV length with an AEAD cipher,iv_len= must be set prior to calling this method.
NOTE: InOpenSSL API conventions, the IV value may correspond to the “nonce” instead in some cipher modes. Refer to theOpenSSL man pages for details.
See also the man page EVP_CipherInit_ex(3).
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static VALUEossl_cipher_iv_length(VALUE self){ EVP_CIPHER_CTX *ctx; int len = 0; GetCipher(self, ctx); if (EVP_CIPHER_flags(EVP_CIPHER_CTX_cipher(ctx)) & EVP_CIPH_FLAG_AEAD_CIPHER) len = (int)(VALUE)EVP_CIPHER_CTX_get_app_data(ctx); if (!len) len = EVP_CIPHER_CTX_iv_length(ctx); return INT2NUM(len);}Returns the expected length in bytes for an IV for thisCipher.
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static VALUEossl_cipher_set_iv_length(VALUE self, VALUE iv_length){ int len = NUM2INT(iv_length); EVP_CIPHER_CTX *ctx; GetCipher(self, ctx); if (!(EVP_CIPHER_flags(EVP_CIPHER_CTX_cipher(ctx)) & EVP_CIPH_FLAG_AEAD_CIPHER)) ossl_raise(eCipherError, "cipher does not support AEAD"); if (!EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, len, NULL)) ossl_raise(eCipherError, "unable to set IV length"); /* * EVP_CIPHER_CTX_iv_length() returns the default length. So we need to save * the length somewhere. Luckily currently we aren't using app_data. */ EVP_CIPHER_CTX_set_app_data(ctx, (void *)(VALUE)len); return iv_length;}Sets the IV/nonce length for thisCipher. This method is available for AEAD ciphers that support variable IV lengths. This method can be called if a different IV length than OpenSSL’s default is desired, prior to callingiv=.
See also the “AEAD Interface” section of the man page EVP_EncryptInit(3). This method internally calls EVP_CIPHER_CTX_ctrl() with EVP_CTRL_AEAD_SET_IVLEN.
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static VALUEossl_cipher_set_key(VALUE self, VALUE key){ EVP_CIPHER_CTX *ctx; int key_len; StringValue(key); GetCipher(self, ctx); key_len = EVP_CIPHER_CTX_key_length(ctx); if (RSTRING_LEN(key) != key_len) ossl_raise(rb_eArgError, "key must be %d bytes", key_len); if (EVP_CipherInit_ex(ctx, NULL, NULL, (unsigned char *)RSTRING_PTR(key), NULL, -1) != 1) ossl_raise(eCipherError, NULL); rb_ivar_set(self, id_key_set, Qtrue); return key;}Sets the cipher key. To generate a key, you should either use a secure random byte string or, if the key is to be derived from a password, you should rely on PBKDF2 functionality provided byOpenSSL::PKCS5. To generate a secure random-based key,Cipher#random_key may be used.
Only call this method after callingCipher#encrypt orCipher#decrypt.
See also the man page EVP_CipherInit_ex(3).
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static VALUEossl_cipher_key_length(VALUE self){ EVP_CIPHER_CTX *ctx; GetCipher(self, ctx); return INT2NUM(EVP_CIPHER_CTX_key_length(ctx));}Returns the key length in bytes of theCipher.
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static VALUEossl_cipher_set_key_length(VALUE self, VALUE key_length){ int len = NUM2INT(key_length); EVP_CIPHER_CTX *ctx; GetCipher(self, ctx); if (EVP_CIPHER_CTX_set_key_length(ctx, len) != 1) ossl_raise(eCipherError, NULL); return key_length;}Sets the key length of the cipher. 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.
Under normal circumstances you do not need to call this method (and probably shouldn’t).
See EVP_CIPHER_CTX_set_key_length for further information.
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static VALUEossl_cipher_name(VALUE self){ EVP_CIPHER_CTX *ctx; GetCipher(self, ctx); return rb_str_new2(EVP_CIPHER_name(EVP_CIPHER_CTX_cipher(ctx)));}Returns the short name of the cipher which may differ slightly from the original name provided.
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static VALUEossl_cipher_set_padding(VALUE self, VALUE padding){ EVP_CIPHER_CTX *ctx; int pad = NUM2INT(padding); GetCipher(self, ctx); if (EVP_CIPHER_CTX_set_padding(ctx, pad) != 1) ossl_raise(eCipherError, NULL); return padding;}Enables or disables padding. 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.
See EVP_CIPHER_CTX_set_padding for further information.
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static VALUEossl_cipher_pkcs5_keyivgen(int argc, VALUE *argv, VALUE self){ EVP_CIPHER_CTX *ctx; const EVP_MD *digest; VALUE vpass, vsalt, viter, vdigest; unsigned char key[EVP_MAX_KEY_LENGTH], iv[EVP_MAX_IV_LENGTH], *salt = NULL; int iter; rb_scan_args(argc, argv, "13", &vpass, &vsalt, &viter, &vdigest); StringValue(vpass); if(!NIL_P(vsalt)){ StringValue(vsalt); if(RSTRING_LEN(vsalt) != PKCS5_SALT_LEN) ossl_raise(eCipherError, "salt must be an 8-octet string"); salt = (unsigned char *)RSTRING_PTR(vsalt); } iter = NIL_P(viter) ? 2048 : NUM2INT(viter); if (iter <= 0) rb_raise(rb_eArgError, "iterations must be a positive integer"); digest = NIL_P(vdigest) ? EVP_md5() : ossl_evp_get_digestbyname(vdigest); GetCipher(self, ctx); EVP_BytesToKey(EVP_CIPHER_CTX_cipher(ctx), digest, salt, (unsigned char *)RSTRING_PTR(vpass), RSTRING_LENINT(vpass), iter, key, iv); if (EVP_CipherInit_ex(ctx, NULL, NULL, key, iv, -1) != 1) ossl_raise(eCipherError, NULL); OPENSSL_cleanse(key, sizeof key); OPENSSL_cleanse(iv, sizeof iv); rb_ivar_set(self, id_key_set, Qtrue); return Qnil;}Generates and sets the key/IV based on a password.
WARNING: This method is deprecated and should not be used. This method corresponds to EVP_BytesToKey(), a non-standardOpenSSL extension of the legacy PKCS #5 v1.5 key derivation function. SeeOpenSSL::KDF for other options to derive keys from passwords.
Parameters¶↑
salt must be an 8 byte string if provided.
iterations is an integer with a default of 2048.
digest is a
Digestobject that defaults to ‘MD5’
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# File ext/openssl/lib/openssl/cipher.rb, line 55defrandom_ivstr =OpenSSL::Random.random_bytes(self.iv_len)self.iv =strend
Generate a random IV withOpenSSL::Random.random_bytes and sets it to the cipher, and returns it.
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# File ext/openssl/lib/openssl/cipher.rb, line 43defrandom_keystr =OpenSSL::Random.random_bytes(self.key_len)self.key =strend
Generate a random key withOpenSSL::Random.random_bytes and sets it to the cipher, and returns it.
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static VALUEossl_cipher_reset(VALUE self){ EVP_CIPHER_CTX *ctx; GetCipher(self, ctx); if (EVP_CipherInit_ex(ctx, NULL, NULL, NULL, NULL, -1) != 1) ossl_raise(eCipherError, NULL); return self;}Fully resets the internal state of theCipher. By using this, the sameCipher instance may be used several times for encryption or decryption tasks.
Internally calls EVP_CipherInit_ex(ctx, NULL, NULL, NULL, NULL, -1).
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static VALUEossl_cipher_update(int argc, VALUE *argv, VALUE self){ EVP_CIPHER_CTX *ctx; unsigned char *in; long in_len, out_len; VALUE data, str; rb_scan_args(argc, argv, "11", &data, &str); if (!RTEST(rb_attr_get(self, id_key_set))) ossl_raise(eCipherError, "key not set"); StringValue(data); in = (unsigned char *)RSTRING_PTR(data); in_len = RSTRING_LEN(data); GetCipher(self, ctx); /* * As of OpenSSL 3.2, there is no reliable way to determine the required * output buffer size for arbitrary cipher modes. * https://github.com/openssl/openssl/issues/22628 * * in_len+block_size is usually sufficient, but AES key wrap with padding * ciphers require in_len+15 even though they have a block size of 8 bytes. * * Using EVP_MAX_BLOCK_LENGTH (32) as a safe upper bound for ciphers * currently implemented in OpenSSL, but this can change in the future. */ if (in_len > LONG_MAX - EVP_MAX_BLOCK_LENGTH) { ossl_raise(rb_eRangeError, "data too big to make output buffer: %ld bytes", in_len); } out_len = in_len + EVP_MAX_BLOCK_LENGTH; if (NIL_P(str)) { str = rb_str_new(0, out_len); } else { StringValue(str); if ((long)rb_str_capacity(str) >= out_len) rb_str_modify(str); else rb_str_modify_expand(str, out_len - RSTRING_LEN(str)); } if (!ossl_cipher_update_long(ctx, (unsigned char *)RSTRING_PTR(str), &out_len, in, in_len)) ossl_raise(eCipherError, NULL); assert(out_len <= RSTRING_LEN(str)); rb_str_set_len(str, out_len); return str;}Encrypts data in a streaming fashion. Hand consecutive blocks of data to theupdate method in order to encrypt it. Returns the encrypted data chunk. When done, the output ofCipher#final should be additionally added to the result.
Ifbuffer is given, the encryption/decryption result will be written to it.buffer will be resized automatically.
NOTE: When decrypting using an AEAD cipher, the integrity of the output is not verified untilfinal has been called.