ElcomSoft has built a utility that forages for encryption keys in snapshots of a PC's memory to decrypt PGP and TrueCrypt-protected data.

Forensic Disk Decryptor attempts to unlock information stored in disks and volumes encrypted by BitLocker, PGP or TrueCrypt. The tool is designed for criminal investigators, IT security bods and forensic specialists. PGP and TrueCrypt set the industry standard for whole-disk or partition encryption.

Normally, the unencrypted content of these data containers is impossible to retrieve without knowing the original passphrase used to encrypt the volume. Vladimir Katalov, chief exec of ElcomSoft, said encryption technology, in the right conditions, can be circumvented thanks to human laziness:

The main and only weakness of crypto containers is human factor. Weak passwords aside, encrypted volumes must be mounted for the user to have on-the-fly access to encrypted data. No one likes typing their long, complex passwords every time they need to read or write a file. As a result, keys used to encrypt and decrypt data that’s being written or read from protected volumes are kept readily accessible in the computer’s operating memory. Obviously, what’s kept readily accessible can be retrieved near instantly by a third-party tool.

ElcomSoft's gear can extract these decryption keys from a copy of the computer's memory, typically captured using a forensic tool or acquired over Firewire. Once it has the key, the protected data can be unlocked.

If the computer is powered off, the analyser can retrieve the keys from a hibernation file on the disk, in which the operating system saves the state of the machine including its main memory, if present and accessible.

“Algorithms allow us to analyse dumps of computers’ volatile memory, locating areas that contain the decryption keys. Sometimes the keys are discovered by analyzing byte sequences, and sometimes by examining crypto containers’ internal structures," Katalov explains.

Encrypted drives must be mounted at the time a memory dump is taken or else the process will fail to work. For this and other reasons, considerable skill and some luck is needed to use the tool properly. Simply tearing the power cable out, thus allowing the RAM to obliterate its contents, if the cops come knocking, or encrypting the hibernation file, can defeat the software.

"Our customers asked us for a tool like this for a long, long time," said Katalov. "We’re finally releasing a product that’s able to access encrypted volumes produced by all three popular crypto containers."

Simon Steggles, director of forensics at data recovery biz Disklabs, said ElcomSoft's utility merely automates a process for retrieving decryption keys that is already used by computer forensics teams, if not the wider IT community.

"In forensics, we have known about this for years. It only works when the computer is switched on. Once it is powered down, the RAM memory is gone and you lose that key," Steggles explained.

"Coincidentally, I looked at the Truecrypt website yesterday and noted that it said on the site that it does on-the-fly encrypting and decrypting, which means that the key must be in the RAM."

The Forensic Disk Decryptor costs £299. ®