diff --git a/target/product/security/README b/target/product/security/README
index 24f984c..15f2e93 100644
--- a/target/product/security/README
+++ b/target/product/security/README
@@ -1,3 +1,14 @@
+For detailed information on key types and image signing, please see:
+
+https://source.android.com/devices/tech/ota/sign_builds.html
+
+The test keys in this directory are used in development only and should
+NEVER be used to sign packages in publicly released images (as that would
+open a major security hole).
+
+key generation
+--------------
+
 The following commands were used to generate the test key pairs:
 
   development/tools/make_key testkey  '/C=US/ST=California/L=Mountain View/O=Android/OU=Android/CN=Android/emailAddress=android@android.com'
@@ -5,18 +16,6 @@
   development/tools/make_key shared   '/C=US/ST=California/L=Mountain View/O=Android/OU=Android/CN=Android/emailAddress=android@android.com'
   development/tools/make_key media    '/C=US/ST=California/L=Mountain View/O=Android/OU=Android/CN=Android/emailAddress=android@android.com'
 
-The following standard test keys are currently included:
-
-testkey -- a generic key for packages that do not otherwise specify a key.
-platform -- a test key for packages that are part of the core platform.
-shared -- a test key for things that are shared in the home/contacts process.
-media -- a test key for packages that are part of the media/download system.
-
-These test keys are used strictly in development, and should never be assumed
-to convey any sort of validity.  When $BUILD_SECURE=true, the code should not
-honor these keys in any context.
-
-
 signing using the openssl commandline (for boot/system images)
 --------------------------------------------------------------
 
@@ -28,7 +27,12 @@
 
 extracting public keys for embedding
 ------------------------------------
-it's a Java tool
-but it generates C code
-take a look at commands/recovery/Android.mk
-you'll see it running $(HOST_OUT_JAVA_LIBRARIES)/dumpkey.jar
+
+dumpkey.jar is a Java tool that takes an x.509 certificate in PEM format as
+input and prints a C structure to standard output:
+
+    $ java -jar out/host/linux-x86/framework/dumpkey.jar build/target/product/security/testkey.x509.pem
+    {64,0xc926ad21,{1795090719,2141396315,950055447,2581568430,4268923165,1920809988,546586521,3498997798,1776797858,3740060814,1805317999,1429410244,129622599,1422441418,1783893377,1222374759,2563319927,323993566,28517732,609753416,1826472888,215237850,4261642700,4049082591,3228462402,774857746,154822455,2497198897,2758199418,3019015328,2794777644,87251430,2534927978,120774784,571297800,3695899472,2479925187,3811625450,3401832990,2394869647,3267246207,950095497,555058928,414729973,1136544882,3044590084,465547824,4058146728,2731796054,1689838846,3890756939,1048029507,895090649,247140249,178744550,3547885223,3165179243,109881576,3944604415,1044303212,3772373029,2985150306,3737520932,3599964420},{3437017481,3784475129,2800224972,3086222688,251333580,2131931323,512774938,325948880,2657486437,2102694287,3820568226,792812816,1026422502,2053275343,2800889200,3113586810,165549746,4273519969,4065247892,1902789247,772932719,3941848426,3652744109,216871947,3164400649,1942378755,3996765851,1055777370,964047799,629391717,2232744317,3910558992,191868569,2758883837,3682816752,2997714732,2702529250,3570700455,3776873832,3924067546,3555689545,2758825434,1323144535,61311905,1997411085,376844204,213777604,4077323584,9135381,1625809335,2804742137,2952293945,1117190829,4237312782,1825108855,3013147971,1111251351,2568837572,1684324211,2520978805,367251975,810756730,2353784344,1175080310}}
+
+This is called by build/core/Makefile to incorporate the OTA signing keys
+into the recovery image.