Secure phones no obstacle to wiretapping – US Govt
The use of so-called secure telephones presents almost no barrier to wiretapping, according to official US government documents.
This interesting revelation is contained in a recent report on Applications for Orders Authorizing or Approving the Interception of Wire, Oral, or Electronic Communications).
The report  (pages 10-11 of report or 8-9 of PDF) states:
Public Law 106-197 amended 18 U.S.C. 2519(2)(b) in 2001 to require that reporting should reflect the number of wiretap applications granted in which encryption was encountered and whether such encryption prevented law enforcement officials from obtaining the plain text of communications intercepted pursuant to the court orders.
In 2002, no federal wiretap reports indicated that encryption was encountered. State and local jurisdictions reported that encryption was encountered in 16 wiretaps terminated in 2002; however, in none of these cases was encryption reported to have prevented law enforcement officials from obtaining the plain text of communications intercepted.
In addition, state and local jurisdictions reported that encryption was encountered in 18 wiretaps that were terminated in calendar year 2001 or earlier, but were reported for the first time in 2002; in none of these cases did encryption prevent access to the plain text of communications intercepted.
Bruce Schneier, the noted cryptographer, deduces from the report that encryption of phone conversations (only encountered in sixteen out of 1,358 wiretaps, so very uncommon) is ineffective at concealing conversations.
"Every time law enforcement encountered encryption, they were able to bypass it," Schneier writes.
"I assume that local law enforcement agencies don't have the means to brute-force DES keys (for example). My guess is that the voice encryption was relatively easy to bypass," he adds.
Schneier argues that the apparently weak security of secure phones is best explained by a lack of peer review.
"Telephone security is a narrow field. Encrypted phones are expensive," he writes in Cryptogram, his excellent monthly newsletter.
"Telephone encryption is closed from scrutiny; the software is not subject to peer review. It should come as no surprise that the result is a poor selection of expensive lousy telephone security products."
Schneier extends his argument beyond the narrow confines of telephone security to criticise the closed security approach (hello TCPA!) in general.
"This wiretapping report provides hard evidence that a closed security design methodology - the 'trust us because we know these things' way of building security products - doesn't work," he concludes. ®
Report of the Director of the Administrative Office of the United States Courts on Applications for Orders Authorizing or Approving the Interception of Wire, Oral, or Electronic Communications (quite a mouthful) 
Schneier's essay on secrecy and security