1# Key Derivation Overview and Algorithm Specifications 2 3A key derivation function (KDF) is a cryptographic algorithm that derives one or more secrete keys from a secret value (such as a master key) by using a pseudorandom function. It can be used to stretch keys into longer keys or to obtain keys in the required format. 4 5## Supported Algorithms and Specifications 6 7### PBKDF2 8 9Password-Based Key Derivation Function (PBKDF) is a key derivation function with a sliding computational cost. PBKDF2 is part of the PKCS series. 10 11PBKDF2 applies a pseudorandom function (PRF), such as [HMAC](crypto-compute-mac.md), to an input password together with a salt value, and repeats the process multiple times to generate a derived key. 12 13When creating a **kDF** instance, you need to specify the algorithm specifications in a string parameter. The string parameter consists of the KDF algorithm and HMAC algorithm with a vertical bar (|) in between. 14| KDF Algorithm| HMAC Algorithm| String Parameter| API Version| 15| -------- | -------- | -------- | -------- | 16| PBKDF2 | SHA1 | PBKDF2\|SHA1 | 11+ | 17| PBKDF2 | SHA224 | PBKDF2\|SHA224 | 11+ | 18| PBKDF2 | SHA256 | PBKDF2\|SHA256 | 11+ | 19| PBKDF2 | SHA384 | PBKDF2\|SHA384 | 11+ | 20| PBKDF2 | SHA512 | PBKDF2\|SHA512 | 11+ | 21| PBKDF2 | SM3 | PBKDF2\|SM3 | 11+ | 22 23### HKDF 24 25HMAC-based Extract-and-Expand Key Derivation Function (HKDF) is a simple key derivation function (KDF) based on the [HMAC](crypto-compute-mac.md) message authentication code. It is used to expand limited input key material into a cryptographically strong secret key. 26 27HKDF consists of two modules: HKDF-Extract and HKDF-Expand. 28 29HKDF-Extract: generates a cryptographic pseudorandom key (PRK) from the input key material and an optional salt. 30 31HKDF-Expand: expands the PRK to a key of the specified length. 32 33When creating a **kDF** instance, you need to specify the algorithm specifications in a string parameter. The string parameter consists of the KDF algorithm, HMAC algorithm, and mode with a vertical bar (|) in between. 34| KDF Algorithm| HMAC Algorithm| String Parameter| API Version| 35| -------- | -------- | -------- | -------- | 36| HKDF | SHA1 | HKDF\|SHA1 | 12+ | 37| HKDF | SHA224 | HKDF\|SHA224 | 12+ | 38| HKDF | SHA256 | HKDF\|SHA256 | 12+ | 39| HKDF | SHA384 | HKDF\|SHA384 | 12+ | 40| HKDF | SHA512 | HKDF\|SHA512 | 12+ | 41| HKDF | SM3 | HKDF\|SM3 | 12+ | 42