All data in Glacier is encrypted. Here's the FAQ entry: > Amazon Glacier handles key management and key protection for you. Amazon Glacier uses one of the stro

All data in Glacier is encrypted. Here's the FAQ entry: > Amazon Glacier handles key management and key protection for you. Amazon Glacier uses one of the strongest block ciphers available, 256-bit Advanced Encryption Standard (AES-256). 256-bit is the largest key size defined for AES. Customers wishing to manage their own keys can encrypt data prior to uploading it.