Module hkdf

Available on crate feature dep_orion only.

HKDF (HMAC-based Extract-and-Expand Key Derivation Function) as specified in the RFC 5869.

Parameters:

• salt: Salt value.
• ikm: Input keying material.
• info: Optional context and application-specific information. If None then it’s an empty string.
• dst_out: Destination buffer for the derived key. The length of the derived key is implied by the length of okm_out.

Errors:

An error will be returned if:

• The length of dst_out is less than 1.
• The length of dst_out is greater than 255 * SHA(256/384/512)_OUTSIZE.

Security:

• Salts should always be generated using a CSPRNG. secure_rand_bytes() can be used for this.
• The recommended length for a salt is 64 bytes.
• Even though a salt value is optional, it is strongly recommended to use one.
• HKDF is not suitable for password storage.

Example:

use orion::{hazardous::kdf::hkdf, util};

let mut salt = [0u8; 64];
util::secure_rand_bytes(&mut salt)?;
let mut okm_out = [0u8; 32];

hkdf::sha512::derive_key(&salt, "IKM".as_bytes(), None, &mut okm_out)?;

Modules

sha256

HKDF-HMAC-SHA256 (HMAC-based Extract-and-Expand Key Derivation Function) as specified in the RFC 5869.

sha384

HKDF-HMAC-SHA384 (HMAC-based Extract-and-Expand Key Derivation Function) as specified in the RFC 5869.

sha512

HKDF-HMAC-SHA512 (HMAC-based Extract-and-Expand Key Derivation Function) as specified in the RFC 5869.