Public/Export-PublicKey.ps1
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# src: https://gist.github.com/therightstuff/aa65356e95f8d0aae888e9f61aa29414 function Export-PublicKey { param ( [Parameter(Mandatory = $true, Position = 0 )] [System.Security.Cryptography.RSACryptoServiceProvider]$csp ) $outputStream = [System.IO.StringWriter]::new() $parameters = $csp.ExportParameters($false); Use ( $stream = [System.IO.MemoryStream]::new()) { $writer = [System.IO.BinaryWriter]::new($stream); $writer.Write([byte]0x30); # SEQUENCE Use ($innerStream = [System.IO.MemoryStream]::new()) { $innerWriter = [System.IO.BinaryWriter]::new($innerStream); $innerWriter.Write([byte]0x30); # SEQUENCE EncodeLength $innerWriter 13 $innerWriter.Write([byte]0x06); # OBJECT IDENTIFIER $rsaEncryptionOid = @(0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x01, 0x01 ) EncodeLength $innerWriter $rsaEncryptionOid.Length $innerWriter.Write($rsaEncryptionOid); $innerWriter.Write([byte]0x05); # NULL EncodeLength $innerWriter 0 $innerWriter.Write([byte]0x03); # BIT STRING Use ($bitStringStream = [System.IO.MemoryStream]::new()) { $bitStringWriter = [System.IO.BinaryWriter]::new($bitStringStream); $bitStringWriter.Write([byte]0x00); # # of unused bits $bitStringWriter.Write([byte]0x30); # SEQUENCE Use ($paramsStream = [System.IO.MemoryStream]::new()) { $paramsWriter = [System.IO.BinaryWriter]::new($paramsStream); EncodeIntegerBigEndian $paramsWriter $parameters.Modulus # Modulus EncodeIntegerBigEndian $paramsWriter $parameters.Exponent # Exponent [int]$paramsLength = $paramsStream.Length; EncodeLength $bitStringWriter $paramsLength $bitStringWriter.Write($paramsStream.GetBuffer(), 0, $paramsLength); } [int]$bitStringLength = $bitStringStream.Length; EncodeLength $innerWriter $bitStringLength $innerWriter.Write($bitStringStream.GetBuffer(), 0, $bitStringLength); } [int]$length = $innerStream.Length; EncodeLength $writer $length $writer.Write($innerStream.GetBuffer(), 0, $length); } $base64 = [System.Convert]::ToBase64String($stream.GetBuffer(), 0, [int]$stream.Length).ToCharArray(); $outputStream.Write("-----BEGIN PUBLIC KEY-----`n"); for ($i = 0; $i -lt $base64.Length; $i += 64) { $outputStream.Write($base64, $i, [System.Math]::Min(64, $base64.Length - $i)); $outputStream.Write("`n"); } $outputStream.Write("-----END PUBLIC KEY-----"); } return $outputStream.ToString(); } |