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Decrypting data (HTML)

The following example shows how to use the Decrypt method to decrypt data.


function decryptDataBuffer(keyMaterial, stringToDecrypt, algNameString, keysize, ivBuffer) {

    // Input arguments:
    //    keyMaterial.......Buffer that contains random key material (same as that used for encryption )
    //    stringToEncrypt...String that contains information to be decrypted
    //    algNameString.....String that contains the name of the symmetric algrorithm to use
    //    keysize...........Requested key size (same as that used for encryption )
    //    ivBuffer..........Buffer that contains the initialization buffer (must match the IV used for encryption)
    
    var decryptedBuffer;
    try {

        // Convert the input string to binary.
        var inputDataBuffer = Windows.Security.Cryptography.CryptographicBuffer.decodeFromBase64String(stringToDecrypt);
            
        // Open the algorithm provider for the algorithm specified on input.
        var algorithmProvider = Windows.Security.Cryptography.Core.SymmetricKeyAlgorithmProvider.openAlgorithm(algNameString);
        if (keysize > algorithmProvider.supportedKeyLengths.max) {
            // Handle error.
        }

        // Create a symmetric key.
        var symmetricKey = algorithmProvider.createSymmetricKey(keyMaterial);
            
        // Check the padding scheme and determine whether the data must be aligned.
        if (algorithmProvider.padding != Windows.Security.Cryptography.Core.CryptographicPadding.block) {
            // Data must be aligned by block size.
            var i = inputDataBuffer.length % algorithmProvider.blockLength;
            if (i > 0) {
                // Handle error.
            }
        }

        // Decrypt the input data.
        decryptedBuffer = Windows.Security.Cryptography.Core.CryptographicEngine.decrypt(symmetricKey, inputDataBuffer, ivBuffer);
     }
    catch (e) {
        // Handle error.
    }       
     
    return decryptedBuffer;
 }

Encrypting and decrypting data