No. 15; Updated March 2011. Click here to download and print a PDF version of this document. Approximately 120,000 children are adopted each year in the United States. Children with physical, developmental, or emotional handicaps who were once considered unadoptable are now being adopted (special needs adoptions). Adoption helps many of these children to grow up in permanent families rather than in foster homes or institutions.
A cryptographic hash function is a hash function which is considered practically impossible to invert, that is, to recreate the input data from its hash value alone.These one-way hash functions have been called the workhorses of modern cryptography.The input data is often called the message, and the hash value is often called the message digest or simply the digest. The ideal cryptographic hash function has four main properties:1  it is easy to compute the hash value for any given message. 2  it is infeasible to generate a message from its hash.hese one-way hash functions have been called the workhorses of modern cryptography. The input data is often called the message, and the hash value is often called the message digest or simply the digest.
A hash function is deemed collision-resistant if it is hard to find two inputs that hash to the same output. Collision-resistant doesn't mean that no collisions exist; simply that they are difficult to find. A successful encryption collision attack on a cryptographic hash function could compromise the security of all kinds of digital systems. For example, many software publishers provide the MD5 (Message-Digest algorithm 5) hash value of their downloadable software.