Some projects in the public maven repositories have their MD5 sums in an alternate format, like so:
fontbox-0.8.0-incubating.jar: 68 7C AB 04 4C 8F 93 7B 89 57 16 62 72 F1 DA 3C
Ivy cannot handle this...it interprets "fontbox-0.8.0-incubating.jar" as the expected MD5 sum, and then concludes that the associated .jar file is corrupt and refuses to use it. The same problem exists for some of the .pom files. This minor issue makes these projects unusable in the maven repo. (So far, I've only found this issue with org.apache.pdfbox and org.apache.fontbox.)
Ideally, Ivy would be able to read the alternate format, but it would probably be acceptable if there were some way to selectively ignore the checksum files.