` | data As `MemoryBlock` | `MemoryBlock` | | ## Enumerations

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Xojo.Crypto.HashAlgorithms ### HashAlgorithms Used by the HMAC, Hash and PBKDF2 methods to specify the type of algorithm to use. (MD5, SHA1, SHA256, SHA512) | Enum | Description | |--------|--------------------------------------------------------------------------------------| | MD5 | [MD5](http://en.wikipedia.org/wiki/MD5) message-digest algorithm. | | SHA1 | [SHA-1](http://en.wikipedia.org/wiki/SHA-1) produces a 160-bit (20-byte) hash value. | | SHA256 | [SHA-2](http://en.wikipedia.org/wiki/SHA-2) with 256 bit digest. | | SHA512 | [SHA-2](http://en.wikipedia.org/wiki/SHA-2) with 512 bit digest. | ## Method descriptions

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Xojo.Crypto.BERDecodePrivateKey **BERDecodePrivateKey**(privateKey As `MemoryBlock`) As `MemoryBlock` Decodes a private key for interoperability with the BER encoding for use by other libraries. For more information, refer to [BER and DER Encoding](http://www.cryptopp.com/wiki/Keys_and_Formats#BER_and_DER_Encoding).

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Xojo.Crypto.BERDecodePublicKey **BERDecodePublicKey**(publicKey As `MemoryBlock`) As `MemoryBlock` Decodes a public key for interoperability with the BER encoding for use by other libraries. For more information, refer to [BER and DER Encoding](http://www.cryptopp.com/wiki/Keys_and_Formats#BER_and_DER_Encoding).

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Xojo.Crypto.DEREncodePrivateKey **DEREncodePrivateKey**(privateKey As `MemoryBlock`) As `MemoryBlock` Encodes a private key for interoperability with the DER encoding for use by other libraries. For more information, refer to [BER and DER Encoding](http://www.cryptopp.com/wiki/Keys_and_Formats#BER_and_DER_Encoding).

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Xojo.Crypto.DEREncodePublicKey **DEREncodePublicKey**(publicKey As `MemoryBlock`) As `MemoryBlock` Encodes a public key for interoperability with the DER encoding for use by other libraries. For more information, refer to [BER and DER Encoding](http://www.cryptopp.com/wiki/Keys_and_Formats#BER_and_DER_Encoding).

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Xojo.Crypto.GenerateRandomBytes **GenerateRandomBytes**(byteCount As `UInteger`) As `MemoryBlock` Generates a random block of data of the specified byteCount. ``` xojo Dim mb1 As New Xojo.Core.MemoryBlock(1024) mb1 = Xojo.Crypto.GenerateRandomBytes(1024) ```

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Xojo.Crypto.Hash **Hash**(data As `MemoryBlock`, algorithm As Xojo.Crypto) As `MemoryBlock` Creates a hash value for the data using the specified algorithm. ``` xojo Using Xojo.Core Using Xojo.Crypto Dim hash As MemoryBlock hash = Hash("YourPasswordSentence", Crypto.HashAlgorithms.SHA512) ```

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Xojo.Crypto.HMAC **HMAC**(key As `MemoryBlock`, data As `MemoryBlock`, algorithm As Xojo.Crypto) As `MemoryBlock` Creates the hash-based message authentication code using the data, the supplied key value and the supplied algorithm. The key value is applied to the data before generating the hash. Refer to [HMAC on wikipedia](http://en.wikipedia.org/wiki/Hash-based_message_authentication_code).

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Xojo.Crypto.MD5 **MD5**(data As `MemoryBlock`) As `MemoryBlock` Generates the [MD5 message-digest](http://en.wikipedia.org/wiki/MD5) value of the data.

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Xojo.Crypto.PBKDF2 **PBKDF2**(salt As `MemoryBlock`, data As `MemoryBlock`, iterations As `UInt32`, desiredHashLength As `UInteger`, hashAlgorithm As Xojo.Crypto) As `MemoryBlock` Returns the PBKDF2 hash value of the data, first applying the salt value and using the specified hashAlgorithm. The iterations parameter is the number of loops that the hash algorithm does. The desiredHashLength parameter lets you specify the number of bytes that you want the resulting hash to be. 16 or 32 bytes are commonly used. PBKDF2 is a "slow", i.e. deliberately processing intensive, algorithm for generating hash values. Slow is relative, for generating a single hash value it is plenty fast. The benefit of a slow algorithm is that it is impractical for hackers to generate hash tables using it because it would take too long to generate the thousands of hashes for commonly used values. Use a higher value for iterations to further slow the hash creation. Refer to [PBKDF2](http://en.wikipedia.org/wiki/Pbkdf2) on Wikipedia. ``` xojo Using Xojo.Core Using Xojo.Crypto Dim salt As Text = "SaltValue" Dim saltMB As MemoryBlock saltMB = Xojo.Core.TextEncoding.UTF8.ConvertTextToData(salt) Dim password As Text = "YourPasswordSentence" Dim passwordMB As MemoryBlock passwordMB = Xojo.Core.TextEncoding.UTF8.ConvertTextToData(password) Dim hash As MemoryBlock hash = PBKDF2(saltMB, passwordMB, 100, 32, HashAlgorithms.SHA512) ```

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Xojo.Crypto.RSADecrypt **RSADecrypt**(data As `MemoryBlock`, privateKey As `MemoryBlock`) As `MemoryBlock` Decrypts data using the specified privateKey.

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Xojo.Crypto.RSAEncrypt **RSAEncrypt**(data As `MemoryBlock`, publicKey As `MemoryBlock`) As `MemoryBlock` Encrypts the data using the specified publicKey. The data that is being encrypted should be kept pretty short (usually just a couple hundred characters, but it depends on the number of bits you use to create the keys). Typically you use the this to communicate a "secret key" of some kind that can be used to decrypt an actual message that was encrypted using some other technique (such as AES).

Warning

A `CryptoException` will be raised if you attempt to encrypt using a private key.

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Xojo.Crypto.RSAGenerateKeyPair **RSAGenerateKeyPair**(bits As `UInteger`, `ByRef` privateKey As `MemoryBlock`, `ByRef` publicKey As `MemoryBlock`) As `Boolean` Generates a private and public key pair that is hex encoded. True if the keys were successfully generated, False if they were not. You will typically use a bits value of 1024 or 2048.

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Xojo.Crypto.RSASign **RSASign**(data As `MemoryBlock`, privateKey As `MemoryBlock`) As `MemoryBlock` Signs the data block using the specified privateKey using PKCS v1.5 with SHA1. Sign a message: ``` xojo Using Xojo.Core Using Xojo.Crypto Dim privateKey As MemoryBlock Dim publicKey As MemoryBlock If RSAGenerateKeyPair( 1024, privateKey, publicKey ) Then ' 1024-bit private and public keys were generated Dim msg As MemoryBlock = TextEncoding.UTF8.ConvertTextToData("this is a test") Dim signature As MemoryBlock = RSASign( msg, privateKey ) If signature <> Nil Then ' msg was successfully signed End If End If ```

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Xojo.Crypto.RSAVerifyKey **RSAVerifyKey**(key As `MemoryBlock`) As `Boolean` Attempts to validate the specified key. True if the signature is valid, False if it is not.

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Xojo.Crypto.RSAVerifySignature **RSAVerifySignature**(data As `MemoryBlock`, signature As `MemoryBlock`, publicKey As `MemoryBlock`) As `Boolean` Verifies the data using the specified signature and key using PKCS v1.5 with SHA1. True if the signature is valid, False if it is not.

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Xojo.Crypto.SHA1 **SHA1**(data As `MemoryBlock`) As `MemoryBlock` Generates the SHA1 hash value for data.

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Xojo.Crypto.SHA256 **SHA256**(data As `MemoryBlock`) As `MemoryBlock` Generates SHA256 hash value for data. ``` xojo Dim t As Text = "TestData" ' Convert text to a MemoryBlock Dim textData As Xojo.Core.MemoryBlock textData = Xojo.Core.TextEncoding.UTF8.ConvertTextToData(t) ' Create SHA256 Dim sha1 As Xojo.Core.MemoryBlock sha1 = Xojo.Crypto.SHA256(textData) ' Convert SHA256 to Text ' Note that this contains invalid UTF8 characters so really ' cannot be displayed Dim sha1Text As Text sha1Text = Xojo.Core.TextEncoding.UTF8.ConvertDataToText(sha1, True) ```

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Xojo.Crypto.SHA512 **SHA512**(data As `MemoryBlock`) As `MemoryBlock` Generates SHA512 hash value for data. ## Compatibility All project types on all supported operating systems. ## See also `MemoryBlock` class