Root > Reference > All Functions > RSASign

Function RSASign

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Signs data.

 

Unit

EEncrypt

 

Syntax

 

Code (Delphi)

function RSASign(

const AKey: TRSAKey;

const AData: Pointer;

const ADataSize: Cardinal

): TRSASignature; overload;

 

function RSASign(

const AKey: TRSAKey;

const AData: TEncryptBuffer

): TRSASignature; overload;

 

function RSASign(

const AKey: TRSAKey;

const AData: RawByteString

): TRSASignature; overload;

 

Parameters

AKey [in]

A key for digital signing. Comes from RSAGenKey function or RSALoadPrivateKey function.

 

AData [in]

Data to be signed.

 

ADataSize [in]

Size of AData in bytes.

 

Return value

Digital signature (little-endian). Release it with SecureFree function.

 

Remarks

This function digitally signs the specified data and returns digital signature. Digital signature is a small RAW bytes value, which can be freely copied and/or exported/imported.

 

Your private key will be used for digital signing.

 

You can verify the returned signature with RSAVerify function.

 

Note

Internally RSASign will calculate SHA-1 hash of AData and sign (encrypt) resulting hash with RSA and private key. EMSA-PKCS1-v1_5 scheme is used for padding.

 

Important!

The resulting signature bytes are in little-endian order. You must reverse bytes order if you want to verify this signature with other tools which requires big-endian order (such as .NET or OpenSSL).

 

Examples

 

Code (Delphi)

var

// Key to sign data

RSAKey: TRSAKey;

// Data to sign

S: String;

// Digital signature for S

Signature: TRSASignature;

begin

// Load private key

RSAKey := RSALoadPrivateKey('C:\Private.pem', rsText, 'Private key password (if any set)');

try

 

// Data to sign

S := 'Some data';

 

// Sign data

Signature := RSASign(RSAKey, Pointer(S), Length(S) * SizeOf(Char));

try

// Clear key as soon as possible

RSADestroyKey(RSAKey);

 

// Store signature somewhere

edSignature.Text := HexEncodeToString(Signature.pbData, Signature.cbData);

 

finally

// Free signature once we finished working with it

SecureFree(Signature);

end;

finally

RSADestroyKey(RSAKey);

end;

end;

 

See also




Send feedback... Build date: 2018-11-26
Last edited: 2018-11-26
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