HKDF

public struct HKDF<H> where H : HashFunction

The HMAC-based Extract-and-Expand Key Derivation Function (IETF RFC 5869) https://tools.ietf.org/html/rfc5869

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  • Derives a symmetric key using the HKDF algorithm.

    Declaration

    Swift

    public static func deriveKey<Salt: DataProtocol, Info: DataProtocol>(inputKeyMaterial: SymmetricKey,
                                                                     salt: Salt,
                                                                     info: Info,
                                                                     outputByteCount: Int) -> SymmetricKey

    Parameters

    inputKeyMaterial

    Input key material.
    salt

    A non-secret random value.
    info

    Context and application specific information.
    outputByteCount

    The desired number of output bytes.

    Return Value

    The derived key

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  • Derives a symmetric key using the HKDF algorithm.

    Declaration

    Swift

    public static func deriveKey<Info: DataProtocol>(inputKeyMaterial: SymmetricKey,
                                                 info: Info,
                                                 outputByteCount: Int) -> SymmetricKey

    Parameters

    inputKeyMaterial

    Input key material.
    info

    Context and application specific information.
    outputByteCount

    The desired number of output bytes.

    Return Value

    The derived key

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  • Derives a symmetric key using the HKDF algorithm.

    Declaration

    Swift

    public static func deriveKey<Salt: DataProtocol>(inputKeyMaterial: SymmetricKey,
                                                 salt: Salt,
                                                 outputByteCount: Int) -> SymmetricKey

    Parameters

    inputKeyMaterial

    Input key material.
    salt

    A non-secret random value.
    outputByteCount

    The desired number of output bytes.

    Return Value

    The derived key

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  • Derives a symmetric key using the HKDF algorithm.

    Declaration

    Swift

    public static func deriveKey(inputKeyMaterial: SymmetricKey,
                             outputByteCount: Int) -> SymmetricKey

    Parameters

    inputKeyMaterial

    Input key material.
    outputByteCount

    The desired number of output bytes.

    Return Value

    The derived key

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  • The extract function as defined by specification. The goal of the extract function is to “concentrate” the possibly dispersed entropy of the input keying material into a short, but cryptographically strong, pseudorandom key. Unless required by a specification, it is recommended to use the one-shot “deriveKey” API instead that performs both extraction and expansion.

    Declaration

    Swift

    public static func extract<Salt>(inputKeyMaterial: SymmetricKey, salt: Salt?) -> HashedAuthenticationCode<H> where Salt : DataProtocol

    Parameters

    inputKeyMaterial

    Input key material.
    salt

    A non-secret random value.

    Return Value

    The resulting secret

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  • The expand function as defined by the specification. The goal of the expand function is to expand the pseudorandom key to the desired length. Unless required by a specification, it is recommended to use the one-shot “deriveKey” API instead that performs both extraction and expansion.

    Declaration

    Swift

    public static func expand<PRK, Info>(pseudoRandomKey prk: PRK, info: Info?, outputByteCount: Int) -> SymmetricKey where PRK : ContiguousBytes, Info : DataProtocol

    Parameters

    pseudoRandomKey

    The extracted pseudorandom key. This value is expected to be a high-entropy secret. In the HKDF specification it is obtained from the input key material and the salt using the extract method.
    info

    Context and application specific information.
    outputByteCount

    The desired number of output bytes.

    Return Value

    The expanded key bytes.

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