# SecKeyRawSign(_:_:_:_:_:_:) Generates a digital signature for a block of data. ``` func SecKeyRawSign(_ key: SecKey, _ padding: SecPadding, _ dataToSign: UnsafePointer, _ dataToSignLen: Int, _ sig: UnsafeMutablePointer, _ sigLen: UnsafeMutablePointer) -> OSStatus ``` ## Parameters `key` Private key with which to sign the data. `padding` The type of padding to use. Possible values are listed in [`SecPadding`](/documentation/Security/SecPadding). Use [`PKCS1SHA1`](/documentation/Security/SecPadding/PKCS1SHA1) if the data to be signed is a SHA1 digest of the actual data. If you specify [`kSecPaddingNone`](/documentation/Security/SecPadding/kSecPaddingNone), the data is signed as-is. `dataToSign` The data to be signed. Typically, a digest of the actual data is signed. `dataToSignLen` Length in bytes of the data in the `dataToSign` buffer. When PKCS1 padding is performed, the maximum length of data that can be signed is 11 bytes less than the value returned by the [`SecKeyGetBlockSize(_:)`](/documentation/Security/SecKeyGetBlockSize(_:)) function (`secKeyGetBlockSize() - 11`). `sig` On return, the digital signature. `sigLen` On entry, the size of the buffer provided in the `sig` parameter. On return, the amount of data actually placed in the buffer. ## Return Value A result code. See [Security Framework Result Codes](/documentation/Security/security-framework-result-codes). ## Discussion The behavior this function with [`kSecPaddingNone`](/documentation/Security/SecPadding/kSecPaddingNone) is undefined if the first byte of the data to sign is `0`; there is no way to verify leading zeroes, as they are discarded during the calculation. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)