DBMS_CRYPTO

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DBMS_CRYPTO provides an interface to encrypt and decrypt stored data, and can be used in conjunction with PL/SQL programs running network communications. It provides support for several industry-standard encryption and hashing algorithms, including the Advanced Encryption Standard (AES) encryption algorithm. AES has been approved by the National Institute of Standards and Technology (NIST) to replace the Data Encryption Standard (DES).

See Also: Oracle Database Security Guide for further information about using this package and about encrypting data in general.

This chapter contains the following topics:

DBMS_CRYPTO Overview

DBMS_CRYPTO contains basic cryptographic functions and procedures. To use this package correctly and securely, a general level of security expertise is assumed.

The DBMS_CRYPTO package enables encryption and decryption for common Oracle datatypes, including RAW and large objects (LOBs), such as images and sound. Specifically, it supports BLOBs and CLOBs. In addition, it provides Globalization Support for encrypting data across different database character sets.

The following cryptographic algorithms are supported:

Data Encryption Standard (DES), Triple DES (3DES, 2-key and 3-key)
Advanced Encryption Standard (AES)
MD5, MD4, SHA-1, and SHA-2 cryptographic hashes
MD5, SHA-1, and SHA-2 Message Authentication Code (MAC)

Block cipher modifiers are also provided with DBMS_CRYPTO. You can choose from several padding options, including PKCS (Public Key Cryptographic Standard) #5, and from four block cipher chaining modes, including Cipher Block Chaining (CBC). Table 48-1 summarizes the DBMS_CRYPTO package features.

Table 1 DBMS_CRYPTO Features

Package Feature	DBMS_CRYPTO
Cryptographic algorithms	DES, 3DES, AES, RC4, 3DES_2KEY
Padding forms	PKCS5, zeroes
Block cipher chaining modes	CBC, CFB, ECB, OFB
Cryptographic hash algorithms	MD5, SHA-1, SHA-2 (SHA-256, SHA-384, SHA-512), MD4
Keyed hash (MAC) algorithms	HMAC_MD5, HMAC_SH1, HMAC_SH256, HMAC_SH384, HMAC_SH512
Cryptographic pseudo-random number generator	`RAW`, `NUMBER`, `BINARY_INTEGER`
Database types	`RAW`, `CLOB`, `BLOB`

The DBMS_CRYPTO package replaces DBMS_OBFUSCATION_TOOLKIT, providing greater ease of use and support for a range of algorithms to accommodate new and existing systems. Specifically, 3DES_2KEY and MD4 are provided for backward compatibility. It is not recommended that you use these algorithms because they do not provide the same level of security as provided by 3DES, AES, MD5, SHA-1, or SHA-2.

DBMS_CRYPTO Security Model

Oracle Database installs this package in the SYS schema. You can then grant package access to existing users and roles as needed.

DBMS_CRYPTO Datatypes

Parameters for the DBMS_CRYPTO subprograms use these datatypes.

Table 2 DBMS_CRYPTO Datatypes

Type	Description
`BLOB`	A source or destination binary LOB
`CLOB`	A source or destination character LOB (excluding NCLOB)
`PLS_INTEGER`	Specifies a cryptographic algorithm type (used with BLOB, CLOB, and RAW datatypes)
`RAW`	A source or destination RAW buffer

DBMS_CRYPTO Algorithms

The DBMS_CRYPTO package contains predefined cryptographic algorithms, modifiers, and cipher suites.

These are shown in the following tables.

Table 3 DBMS_CRYPTO Cryptographic Hash Functions

Name	Description
`HASH_MD4`	Produces a 128-bit hash, or message digest of the input message
`HASH_MD5`	Also produces a 128-bit hash, but is more complex than MD4
`HASH_SH1`	Secure Hash Algorithm (SHA-1). Produces a 160-bit hash.
`HASH_SH256`	SHA-2, produces a 256-bit hash.
`HASH_SH384`	SHA-2, produces a 384-bit hash.
`HASH_SH512`	SHA-2, produces a 512-bit hash.

Table 4 DBMS_CRYPTO MAC (Message Authentication Code) Functions

Name	Description
`HMAC_MD5`Foot 1	Same as MD5 hash function, except it requires a secret key to verify the hash value.
`HMAC_SH1`Foot 1	Same as SHA hash function, except it requires a secret key to verify the hash value.
`HMAC_SH256`	Same as SHA-2 256-bit hash function, except it requires a secret key to verify the hash value.
`HMAC_SH384`	Same as SHA-2 384-bit hash function, except it requires a secret key to verify the hash value.
`HMAC_SH512`	Same as SHA-2 512-bit hash function, except it requires a secret key to verify the hash value.

Footnote 1

Complies with IETF RFC 2104 standard

Table 5 DBMS_CRYPTO Encryption Algorithms

Name	Description
`ENCRYPT_DES`	Data Encryption Standard. Block cipher. Uses key length of 56 bits.
`ENCRYPT_3DES_2KEY`	Data Encryption Standard. Block cipher. Operates on a block 3 times with 2 keys. Effective key length of 112 bits.
`ENCRYPT_3DES`	Data Encryption Standard. Block cipher. Operates on a block 3 times.
`ENCRYPT_AES128`	Advanced Encryption Standard. Block cipher. Uses 128-bit key size.
`ENCRYPT_AES192`	Advanced Encryption Standard. Block cipher. Uses 192-bit key size.
`ENCRYPT_AES256`	Advanced Encryption Standard. Block cipher. Uses 256-bit key size.
`ENCRYPT_RC4`	Stream cipher. Uses a secret, randomly generated key unique to each session.

Table 6 DBMS_CRYPTO Block Cipher Suites

Name	Description
`DES_CBC_PKCS5`	ENCRYPT_DESFoot 2 + CHAIN_CBCFoot 3+ PAD_PKCS5Foot 4
`DES3_CBC_PKCS5`	`ENCRYPT_3DES`Foot 2 + `CHAIN_CBC`Foot 3 + PAD_PKCS5Foot 4

Footnote 2

See Table 48-5

Footnote 3

See Table 48-7

Footnote 4

See Table 48-8

Table 7 DBMS_CRYPTO Block Cipher Chaining Modifiers

Name	Description
`CHAIN_ECB`	Electronic Codebook. Encrypts each plaintext block independently.
`CHAIN_CBC`	Cipher Block Chaining. Plaintext is XORed with the previous ciphertext block before it is encrypted.
`CHAIN_CFB`	Cipher-Feedback. Enables encrypting units of data smaller than the block size.
`CHAIN_OFB`	Output-Feedback. Enables running a block cipher as a synchronous stream cipher. Similar to CFB, except that n bits of the previous output block are moved into the right-most positions of the data queue waiting to be encrypted.

Table 8 DBMS_CRYPTO Block Cipher Padding Modifiers

Name	Description
`PAD_PKCS5`	Provides padding which complies with the PKCS #5: Password-Based Cryptography Standard
`PAD_NONE`	Provides option to specify no padding. Caller must ensure that blocksize is correct, else the package returns an error.
`PAD_ZERO`	Provides padding consisting of zeroes

DBMS_CRYPTO Restrictions

The VARCHAR2 datatype is not directly supported by DBMS_CRYPTO. Before you can perform cryptographic operations on data of the type VARCHAR2, you must convert it to the uniform database character set AL32UTF8, and then convert it to the RAW datatype. After performing these conversions, you can then encrypt it with the DBMS_CRYPTO package.

See Also: DBMS_CRYPTO Operational Notes for information about the conversion rules for converting datatypes.

DBMS_CRYPTO Exceptions

The following table lists exceptions that have been defined for DBMS_CRYPTO.

Table 9 DBMS_CRYPTO Exceptions

Exception	Code	Description
`CipherSuiteInvalid`	`28827`	The specified cipher suite is not defined.
`CipherSuiteNull`	`28829`	No value has been specified for the cipher suite to be used.
`KeyNull`	`28239`	The encryption key has not been specified or contains a `NULL` value.
`KeyBadSize`	`28234`	DES keys: Specified key size is too short. DES keys must be at least 8 bytes (64 bits). AES keys: Specified key size is not supported. AES keys must be 128, 192, or 256 bits in length.
`DoubleEncryption`	`28233`	Source data was previously encrypted.

DBMS_CRYPTO Operational Notes

This section describes several DBMS_CRYPTO operational notes.

When to Use Encrypt and Decrypt Procedures or Functions
When to Use Hash or Message Authentication Code (MAC) Functions
About Generating and Storing Encryption Keys
Conversion Rules

When to Use Encrypt and Decrypt Procedures or Functions

This package includes both ENCRYPT and DECRYPT procedures and functions. The procedures are used to encrypt or decrypt LOB datatypes (overloaded for CLOB and BLOB datatypes). In contrast, the ENCRYPT and DECRYPT functions are used to encrypt and decrypt RAW datatypes. Data of type VARCHAR2 must be converted to RAW before you can use DBMS_CRYPTO functions to encrypt it.

When to Use Hash or Message Authentication Code (MAC) Functions

This package includes two different types of one-way hash functions: the HASH function and the MAC function. Hash functions operate on an arbitrary-length input message, and return a fixed-length hash value. One-way hash functions work in one direction only. It is easy to compute a hash value from an input message, but it is extremely difficult to generate an input message that hashes to a particular value. Note that hash values should be at least 128 bits in length to be considered secure.

You can use hash values to verify whether data has been altered. For example, before storing data, the user runs DBMS_CRYPTO.HASH against the stored data to create a hash value. On returning the stored data, the user can again run the hash function against it, using the same algorithm. If the second hash value is identical to the first one, then the data has not been altered. Hash values are similar to “file fingerprints” and are used to ensure data integrity.

The HASH function included with DBMS_CRYPTO, is a one-way hash function that you can use to generate a hash value from either RAW or LOB data. The MAC function is also a one-way hash function, but with the addition of a secret key. It works the same way as the DBMS_CRYPTO.HASH function, except only someone with the key can verify the hash value.

MACs can be used to authenticate files between users. They can also be used by a single user to determine if her files have been altered, perhaps by a virus. A user could compute the MAC of his files and store that value in a table. If the user did not use a MAC function, then the virus could compute the new hash value after infection and replace the table entry. A virus cannot do that with a MAC because the virus does not know the key.

About Generating and Storing Encryption Keys

The DBMS_CRYPTO package can generate random material for encryption keys, but it does not provide a mechanism for maintaining them. Application developers must take care to ensure that the encryption keys used with this package are securely generated and stored. Also note that the encryption and decryption operations performed by DBMS_CRYPTO occur on the server, not on the client. Consequently, if the key is sent over the connection between the client and the server, the connection must be protected by using network encryption. Otherwise, the key is vulnerable to capture over the wire.

Although DBMS_CRYPTO cannot generate keys on its own, it does provide tools you can use to aid in key generation. For example, you can use the RANDOMBYTES function to generate random material for keys.

When generating encryption keys for DES, it is important to remember that some numbers are considered weak and semiweak keys. Keys are considered weak or semiweak when the pattern of the algorithm combines with the pattern of the initial key value to produce ciphertext that is more susceptible to cryptanalysis. To avoid this, filter out the known weak DES keys. Lists of the known weak and semiweak DES keys are available on several public Internet sites.

See Also:

Oracle Database Security Guide for information about configuring network encryption and SSL
RANDOMBYTES Function

Conversion Rules

To convert VARCHAR2 to RAW, use the UTL_I18N.STRING_TO_RAW function to perform the following steps:
1. Convert VARCHAR2 in the current database character set to VARCHAR2 in the AL32UTF8 database character.
2. Convert VARCHAR2 in the AL32UTF8 database character set to RAW.
Syntax example:

UTL_I18N.STRING_TO_RAW (string, 'AL32UTF8');

To convert RAW to VARCHAR2, use the UTL_I18N.RAW_TO_CHAR function to perform the following steps:
1. Convert RAW to VARCHAR2 in the AL32UTF8 database character set.
2. Convert VARCHAR2 in the AL32UTF8 database character set to VARCHAR2 in the database character set you wish to use.
Syntax example:

UTL_I18N.RAW_TO_CHAR (data, 'AL32UTF8');

See Also: UTL_I18N for information about using the UTL_I18N PL/SQL package.

If you want to store encrypted data of the RAW datatype in a VARCHAR2 database column, then use RAWTOHEX or UTL_ENCODE.BASE64_ENCODE to make it suitable for VARCHAR2 storage. These functions expand data size by 2 and 4/3, respectively.

DBMS_CRYPTO Examples

This listing shows PL/SQL block encrypting and decrypting pre-defined ‘input_string’ using 256-bit AES algorithm with Cipher Block Chaining and PKCS#5 compliant padding.

DECLARE
   input_string       VARCHAR2 (200) :=  'Secret Message';
   output_string      VARCHAR2 (200);
   encrypted_raw      RAW (2000);             -- stores encrypted binary text
   decrypted_raw      RAW (2000);             -- stores decrypted binary text
   num_key_bytes      NUMBER := 256/8;        -- key length 256 bits (32 bytes)
   key_bytes_raw      RAW (32);               -- stores 256-bit encryption key
   encryption_type    PLS_INTEGER :=          -- total encryption type

                            DBMS_CRYPTO.ENCRYPT_AES256
                          + DBMS_CRYPTO.CHAIN_CBC
                          + DBMS_CRYPTO.PAD_PKCS5;

   iv_raw             RAW (16);

BEGIN
   DBMS_OUTPUT.PUT_LINE ( 'Original string: ' || input_string);
   key_bytes_raw := DBMS_CRYPTO.RANDOMBYTES (num_key_bytes);
   iv_raw        := DBMS_CRYPTO.RANDOMBYTES (16);
   encrypted_raw := DBMS_CRYPTO.ENCRYPT
      (
         src => UTL_I18N.STRING_TO_RAW (input_string,  'AL32UTF8'),
         typ => encryption_type,
         key => key_bytes_raw,
         iv  => iv_raw
      );

    -- The encrypted value "encrypted_raw" can be used here

    decrypted_raw := DBMS_CRYPTO.DECRYPT
      (
         src => encrypted_raw,
         typ => encryption_type,
         key => key_bytes_raw,
         iv  => iv_raw
      );

   output_string := UTL_I18N.RAW_TO_CHAR (decrypted_raw, 'AL32UTF8');

   DBMS_OUTPUT.PUT_LINE ('Decrypted string: ' || output_string);
END;

Summary of DBMS_CRYPTO Subprograms

This table lists the DBMS_CRYPTO subprograms in alphabetical order and briefly describes them.

Table 10 DBMS_CRYPTO Package Subprograms

Subprogram	Description
DECRYPT Function	Decrypts `RAW` data using a stream or block cipher with a user supplied key and optional IV (initialization vector)
DECRYPT Procedures	Decrypts `LOB` data using a stream or block cipher with a user supplied key and optional IV
ENCRYPT Function	Encrypts `RAW` data using a stream or block cipher with a user supplied key and optional IV
ENCRYPT Procedures	Encrypts `LOB` data using a stream or block cipher with a user supplied key and optional IV
HASH Function	Applies one of the supported cryptographic hash algorithms (MD4, MD5, SHA-1, or SHA-2) to data
MAC Function	Applies Message Authentication Code algorithms (MD5, SHA-1, or SHA-2) to data to provide keyed message protection
RANDOMBYTES Function	Returns a `RAW` value containing a cryptographically secure pseudo-random sequence of bytes, and can be used to generate random material for encryption keys
PKDECRYPT Function	Decrypts `RAW` data using a private key assisted with key algorithm and encryption algorithm and returns decrypted data.
PKENCRYPT Function	Encrypts `RAW` data using a public key assisted with key algorithm and encryption algorithm and returns encrypted data
RANDOMINTEGER Function	Returns a random `BINARY_INTEGER`
RANDOMNUMBER Function	Returns a random 128-bit integer of the `NUMBER` datatype
SIGN Function	Signs `RAW` data using a private key assisted with key algorithm and sign algorithm, and returns a signature
VERIFY Function	Verifies `RAW` data using the signature, public key assisted with key algorithm, and sign algorithm. It returns `TRUE` if the signature was verified

DECRYPT Function

This function decrypts RAW data using a stream or block cipher with a user supplied key and optional IV (initialization vector).

Syntax

DBMS_CRYPTO.DECRYPT(
   src IN RAW,
   typ IN PLS_INTEGER,
   key IN RAW,
   iv  IN RAW DEFAULT NULL)
 RETURN RAW;

Pragmas

pragma restrict_references(decrypt,WNDS,RNDS,WNPS,RNPS);

Parameters

Table 11 DECRYPT Function Parameters

Parameter Name	Description
`src`	`RAW` data to be decrypted.
`typ`	Stream or block cipher type and modifiers to be used.
`key`	Key to be used for decryption.
`iv`	Optional initialization vector for block ciphers. Default is `NULL`.

Usage Notes

To retrieve original plaintext data, DECRYPT must be called with the same cipher, modifiers, key, and IV that was used to encrypt the data originally.

See Also: “Usage Notes” for the ENCRYPT function for additional information about the ciphers and modifiers available with this package.
If VARCHAR2 data is converted to RAW before encryption, then it must be converted back to the appropriate database character set by using the UTL_I18N package.

See Also: DBMS_CRYPTO Operational Notes for a discussion of the VARCHAR2 to RAW conversion rules

DECRYPT Procedures

These procedures decrypt LOB data using a stream or block cipher with a user supplied key and optional IV (initialization vector).

Syntax

DBMS_CRYPTO.DECRYPT(
   dst IN OUT NOCOPY BLOB,
   src IN            BLOB,
   typ IN            PLS_INTEGER,
   key IN            RAW,
   iv  IN            RAW          DEFAULT NULL);

DBMS_CRYPT.DECRYPT(
   dst IN OUT NOCOPY CLOB         CHARACTER SET ANY_CS,
   src IN            BLOB,
   typ IN            PLS_INTEGER,
   key IN            RAW,
   iv  IN            RAW          DEFAULT NULL);

Pragmas

pragma restrict_references(decrypt,WNDS,RNDS,WNPS,RNPS);

Parameters

Table 12 DECRYPT Procedure Parameters

Parameter Name	Description
dst	`LOB` locator of output data. The value in the output `LOB` <`dst`> will be overwritten.
`src`	`LOB` locator of input data.
`typ`	Stream or block cipher type and modifiers to be used.
`key`	Key to be used for decryption.
`iv`	Optional initialization vector for block ciphers. Default is all zeroes.

ENCRYPT Function

This function encrypts RAW data using a stream or block cipher with a user supplied key and optional IV (initialization vector).

Syntax

DBMS_CRYPTO.ENCRYPT(
   src IN RAW,
   typ IN PLS_INTEGER,
   key IN RAW,
   iv  IN RAW          DEFAULT NULL)
 RETURN RAW;

Pragmas

pragma restrict_references(encrypt,WNDS,RNDS,WNPS,RNPS);

Parameters

Table 13 ENCRYPT Function Parameters

Parameter Name	Description
`src`	`RAW` data to be encrypted.
`typ`	Stream or block cipher type and modifiers to be used.
`key`	Encryption key to be used for encrypting data.
`iv`	Optional initialization vector for block ciphers. Default is `NULL`.

Usage Notes

Block ciphers may be modified with chaining and padding type modifiers. The chaining and padding type modifiers are added to the block cipher to produce a cipher suite. Cipher Block Chaining (CBC) is the most commonly used chaining type, and PKCS #5 is the recommended padding type. See Table 48-7 and Table 48-8 for block cipher chaining and padding modifier constants that have been defined for this package.
To improve readability, you can define your own package-level constants to represent the cipher suites you use for encryption and decryption. For example, the following example defines a cipher suite that uses DES, cipher block chaining mode, and no padding:

DES_CBC_NONE CONSTANT PLS_INTEGER := DBMS_CRYPTO.ENCRYPT_DES

                                     + DBMS_CRYPTO.CHAIN_CBC

                                     + DBMS_CRYPTO.PAD_NONE;

See Table 48-6 for the block cipher suites already defined as constants for this package.

To encrypt VARCHAR2 data, it should first be converted to the AL32UTF8 character set.

See Also: The discussion of conversion rules under DBMS_CRYPTO Operational Notes
Stream ciphers, such as RC4, are not recommended for stored data encryption.

ENCRYPT Procedures

These procedures encrypt LOB data using a stream or block cipher with a user supplied key and optional IV (initialization vector).

Syntax

DBMS_CRYPTO.ENCRYPT(
   dst IN OUT NOCOPY BLOB,
   src IN            BLOB,
   typ IN            PLS_INTEGER,
   key IN            RAW,
   iv  IN            RAW          DEFAULT NULL);

DBMS_CRYPTO.ENCRYPT(
   dst IN OUT NOCOPY BLOB,
   src IN            CLOB         CHARACTER SET ANY_CS,
   typ IN            PLS_INTEGER,
   key IN            RAW,
   iv  IN            RAW          DEFAULT NULL);

Pragmas

pragma restrict_references(encrypt,WNDS,RNDS,WNPS,RNPS);

Parameters

Table 14 ENCRYPT Procedure Parameters

Parameter Name	Description
dst	`LOB` locator of output data. The value in the output `LOB` <`dst`> will be overwritten.
`src`	`LOB` locator of input data.
`typ`	Stream or block cipher type and modifiers to be used.
`key`	Encryption key to be used for encrypting data.
`iv`	Optional initialization vector for block ciphers. Default is `NULL`.

Usage Notes

See DBMS_DEBUG Operational Notes for more information about the conversion rules for the ENCRYPT procedure.

HASH Function

A one-way hash function takes a variable-length input string, the data, and converts it to a fixed-length (generally smaller) output string called a hash value. The hash value serves as a unique identifier (like a fingerprint) of the input data. You can use the hash value to verify whether data has been changed or not.

Note that a one-way hash function is a hash function that works in one direction. It is easy to compute a hash value from the input data, but it is hard to generate data that hashes to a particular value. Consequently, one-way hash functions work well to ensure data integrity. Refer to “When to Use Hash or Message Authentication Code (MAC) Functions” in DBMS_CRYPTO Operational Notes for more information about using one-way hash functions.

This function applies to data one of the supported cryptographic hash algorithms listed in Table 48-3.

Syntax

DBMS_CRYPTO.Hash (
   src IN RAW,
   typ IN PLS_INTEGER)
 RETURN RAW;

DBMS_CRYPTO.Hash (
   src IN BLOB,
   typ IN PLS_INTEGER)
 RETURN RAW;

DBMS_CRYPTO.Hash (
   src IN CLOB CHARACTER SET ANY_CS,
   typ IN PLS_INTEGER)
 RETURN RAW;

Pragmas

pragma restrict_references(hash,WNDS,RNDS,WNPS,RNPS);

Parameters

Table 15 HASH Function Parameters

Parameter Name	Description
`src`	The source data to be hashed.
`typ`	The hash algorithm to be used.

Usage Note

Oracle recommends that you use the SHA-1 (Secure Hash Algorithm) or SHA-2 because it is more resistant to brute-force attacks than MD4 or MD5. If you must use a Message Digest algorithm, then MD5 provides greater security than MD4.

MAC Function

This function applies Message Authentication Code (MAC) algorithms to data to provide keyed message protection.

A MAC is a key-dependent one-way hash function. MACs have the same properties as the one-way hash function described in HASH Function, but they also include a key. Only someone with the identical key can verify the hash. Also refer to “When to Use Hash or Message Authentication Code (MAC) Functions” in DBMS_CRYPTO Operational Notes for more information about using MACs.

See Table 48-4 for a list of MAC algorithms that have been defined for this package.

Syntax

DBMS_CRYPTO.MAC (
   src IN RAW,
   typ IN PLS_INTEGER,
   key IN RAW)
 RETURN RAW;

DBMS_CRYPTO.MAC (
   src IN BLOB,
   typ IN PLS_INTEGER
   key IN RAW)
 RETURN RAW;

DBMS_CRYPTO.MAC (
   src IN CLOB CHARACTER SET ANY_CS,
   typ IN PLS_INTEGER
   key IN RAW)
 RETURN RAW;

Pragmas

pragma restrict_references(mac,WNDS,RNDS,WNPS,RNPS);

Parameters

Table 16 MAC Function Parameters

Parameter Name	Description
`src`	Source data to which MAC algorithms are to be applied.
`typ`	MAC algorithm to be used.
`key`	Key to be used for MAC algorithm.

PKDECRYPT Function

This function decrypts RAW data using a private key assisted with key algorithm and encryption algorithm and returns decrypted data.

Syntax

DBMS_CRYPTO.PKDECRYPT(
   src IN RAW,
   prv_key IN RAW,
   pubkey_alg IN BINARY_INTEGER,
   enc_alg  IN BINARY_INTEGER)
 RETURN RAW;

Parameters

Table 17 PKDECRYPT Function Parameters

Parameter Name	Description
`src`	`RAW` data to be decrypted.
`prv_key`	Private key.
`pubkey_alg`	Specify the KEY_TYPE_RSA RSA key type.
`enc_alg`	Specify the algorithm PKENCRYPT_RSA_PKCS1_OAEP, for RSA Public Key Cryptosystem with PKCS1 and OAEP padding.

PKENCRYPT Function

This function encrypts RAW data using a public key assisted with key algorithm and encryption algorithm and returns encrypted data.

Syntax

DBMS_CRYPTO.PKENCRYPT(
   src IN RAW,
   pub_key IN RAW,
   pubkey_alg IN BINARY_INTEGER,
   enc_alg  IN BINARY_INTEGER)
 RETURN RAW;

Parameters

Table 18 PKENCRYPT Function Parameters

Parameter Name	Description
`src`	`RAW` data to be encrypted.
`pub_key`	Public key.
`pubkey_alg`	Specify the KEY_TYPE_RSA RSA key type.
`enc_alg`	Specify the algorithm PKENCRYPT_RSA_PKCS1_OAEP, for RSA Public Key Cryptosystem with PKCS1 and OAEP padding.

RANDOMBYTES Function

This function returns a RAW value containing a cryptographically secure pseudo-random sequence of bytes, which can be used to generate random material for encryption keys.

The RANDOMBYTES function is based on the RSA X9.31 PRNG (Pseudo-Random Number Generator).

Syntax

DBMS_CRYPTO.RANDOMBYTES (
   number_bytes IN POSITIVE)
 RETURN RAW;

Pragmas

pragma restrict_references(randombytes,WNDS,RNDS,WNPS,RNPS);

Parameters

Table 19 RANDOMBYTES Function Parameter

Parameter Name	Description
`number_bytes`	The number of pseudo-random bytes to be generated.

Usage Note

The number_bytes value should not exceed the maximum length of a RAW variable.

RANDOMINTEGER Function

This function returns an integer in the complete range available for the Oracle BINARY_INTEGER datatype.

Syntax

DBMS_CRYPTO.RANDOMINTEGER
 RETURN BINARY_INTEGER;

Pragmas

pragma restrict_references(randominteger,WNDS,RNDS,WNPS,RNPS);

RANDOMNUMBER Function

This function returns an integer in the Oracle NUMBER datatype in the range of [0..2**128-1].

Syntax

DBMS_CRYPTO.RANDOMNUMBER
 RETURN NUMBER;

Pragmas

pragma restrict_references(randomnumber,WNDS,RNDS,WNPS,RNPS);

SIGN Function

This function signs RAW data using a private key assisted with key algorithm and sign algorithm, and returns a signature.

Syntax

DBMS_CRYPTO.SIGN(
   src IN RAW,
   prv_key IN RAW,
   pubkey_alg IN BINARY_INTEGER,
   sign_alg IN BINARY_INTEGER)
 RETURN RAW;

Parameters

Table 20 SIGN Function Parameters

Parameter Name	Description
`src`	`RAW` data to be signed.
`prv_key`	Private key.
`pubkey_alg`	Specify the KEY_TYPE_RSA RSA key type.
`sign_alg`	Specify one of the algorithms that are listed in the Usage Notes.

Usage Notes

Table 21 SHA Hash Algorithms

Hash Algorithm	Description
SIGN_SHA1_RSA	SHA1 hash function with RSA
SIGN_SHA1_RSA_X931	SHA1 hash function with RSA and X931 padding
SIGN_SHA224_RSA	SHA 224 bit hash function with RSA
SIGN_SHA256_RSA	SHA 256 bit hash function with RSA
SIGN_SHA256_RSA_X931	SHA 256 bit hash function with RSA and X931 padding
SIGN_SHA384_RSA	SHA 384 bit hash function with RSA
SIGN_SHA384_RSA_X931	SHA 384 bit hash function with RSA and X931 padding
SIGN_SHA512_RSA	SHA 384 bit hash function with RSA
SIGN_SHA512_RSA_X931	SHA 384 bit hash function with RSA and X931 padding

VERIFY Function

This function verifies RAW data using the signature, public key assisted with key algorithm, and sign algorithm. It returns TRUE if the signature was verified.

Syntax

DBMS_CRYPTO.VERIFY(
   src IN RAW,
   sign IN RAW,
   pub_key IN RAW,
   pubkey_alg IN BINARY_INTEGER,
   sign_alg  IN BINARY_INTEGER)
 RETURN BOOLEAN;

Parameters

Table 22 VERIFY Function Parameters

Parameter Name	Description
`src`	`RAW` data to be verified.
`sign`	Message signature.
`pub_key`	Public key.
`pubkey_alg`	Specify the KEY_TYPE_RSA RSA key type.
`sign_alg`	Specify one of the algorithms that are listed the Usage Notes.

Usage Notes

Table 23 SHA Hash Algorithms

Hash Algorithm	Description
SIGN_SHA1_RSA	SHA hash function with RSA
SIGN_SHA1_RSA_X931	SHA hash function with RSA and X931 padding
SIGN_SHA224_RSA	SHA 224 bit hash function with RSA
SIGN_SHA256_RSA	SHA 256 bit hash function with RSA
SIGN_SHA256_RSA_X931	SHA 256 bit hash function with RSA and X931 padding
SIGN_SHA384_RSA	SHA 384 bit hash function with RSA
SIGN_SHA384_RSA_X931	SHA 384 bit hash function with RSA and X931 padding
SIGN_SHA512_RSA	SHA 384 bit hash function with RSA
SIGN_SHA512_RSA_X931	SHA 384 bit hash function with RSA and X931 padding