Apex(Salesforce): Generating base-64 SHA1 Hash for Rackspace API Signature Headers

Base64SHA1Hash.java

//Example String to be passed for SHA1 hash generation 
String targetString = 'eGbq9/2hcZsRlr1JV1PiRackspace Management Interface20010308143725QHOvchm/40czXhJ1OxfxK7jDHr3t';
// Convert to BLOB
Blob targetBlob = Blob.valueOf(targetString);
// Generate SHA1 digest
Blob hashSHA1 = Crypto.generateDigest('SHA1', targetBlob);
// For Rackspace Compatiblity encode the binary into BASE 64
// this will result in 28 chars long string 
String hashBase64SHA1 = EncodingUtil.base64encode (hashSHA1);
// should print :  "46VIwd66mOFGG8IkbgnLlXnfnkU="
System.debug (hashBase64SHA1);